ML20084F321

RO 250-75-3:on 751105,spring Hanger on Main Steam Line 3A Inside Containment Found Distorted.Cause Unknown.Plant Change/Mod Being Generated to Provide New Hanger Design to Withstand Spurious Closure Load & Hydro & Test Loads

ML20084F321
Person / Time
Site:	Turkey Point
Issue date:	12/05/1975
From:	Schmidt A FLORIDA POWER & LIGHT CO.
To:	Moseley N NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION II)
References
RO-250-75-3, NUDOCS 8304210097
Download: ML20084F321 (2)

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c.,.k._ jM p.e. sox sioo minM noaioA resioi s n fY__. pr u 'Lt ' L_: cert FLORIDA POWER & UGHT COMPANY December 5, 1975 PRN-LI-75-8 Mr. Norman C. Moseley, Director, Region II J' Office of Inspection and Enforcement /$,) -

U. S. Nuclear Regulatory Commission 6p',, , ,

230 Peachtree Street, N.W., Suite 818 'f ..

l Atlanta, Georgia 30303 .

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Dear Mr. Moseley:

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'd UNUSUAL EVENT 250-75-3 ',' s ,

TURKEY POINT UNIT 3 ' 4 DISTORTION OF 3A MAIN STEAM - .

LINE SPRING SUPPORT A ., DESCRIPTION OF EVENT The Unit 3 reactor was in the refueling shutdown condition.

On_ November 5,'1975, the spring hanger on the 3A Main Steam line inside containment was found to be distorted. The hanger was a spring compression support combined with a link assembly-for flexibility. The hanger distortion was shown to a Nuclear Regulatory Commission inspector who was on-site at the time.

B. APPARENT CAUSE AND ANALYSIS OF EVENT The occ_urrence was not witnessed so the exact cause is un-known, however, a recent spurious closure of the 3A Main SFeam Isolation Valve (MSIV) at full powdr may have generated enough transient load to distort the hanger. The hanger had been originally designed to withstand hydrostatic test and dead loads. Distortion of the hanger indicates'that the load generated during the occurrence was absorbed by the hanger thereby pro-t.ecti_ng the Main Steam piping.

Visual examination has shown no degradation of the Main Steam piping in the area of the hanger-to-piping weld. A-liquid penetrant examination will'be conducted to verify _this.

C. CORRECTIVE ACTION A Plant Change / Modification (PC/M) is being generated to pro-g vide a new hanger designed to withstand the spurious closure load as well as the hydro and test loads. The parts for the-new design hanger have been received and work to install the hanger will begin upon final approval of the'PC/M. The new hanger will be installed-before the end of the current re-

-fueling outage. .

8304210097 751205 13844 PDR ADDCK 050002gg S

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l l Mr. Norman C. Moseley, Director, Region II -

l l Page Two l- December 5, 1975 .

l l In addition, the hangers on the 3B, 3C, 4A, 4L, and-4C Main Steam lines are being evaluated to determine if their design requires improvement. If the final evaluation leads to a change in the design of any to these hangers, a supplementary report will be issued.

Very truly yours, nl/?/f ou&~

pt,A. D. Schmidt

/ Vice Pr,esident Power Resources MAS /ms .

cc: Jack R. Newman, Esquire Director, Office of Inspection and Enforcement (30)

Director, Office of Management Information and Program Control (3)

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