ML20148F401

Notifies That Addl Info Available,Supplementing AEC 721209 Telegram,Re Relief Valve Failure on Secondary Side of PWR Steam Generator.Safety & Relief Valve Installation Stress Analysis re-evaluation to Be Discussed at Next Insp

ML20148F401
Person / Time
Site:	Yankee Rowe
Issue date:	04/21/1972
From:	James O'Reilly NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION I)
To:	Minnick L YANKEE ATOMIC ELECTRIC CO.
References
NUDOCS 8011050613
Download: ML20148F401 (1)

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ATOMIC ENERGY COMMISfv N DIVISloN OF CoMPL.t ANcc- 2ol 645 3

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4, nEGION I 97o DROAD STREET NEWARK. NEW JERSFY o71o2 0 b

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. APR ~o 1 l972

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( Yanhec Atomic Electric Company ' Docket No. 50- 29 l

Attention: Mr. L. E. !!innich

, Vice President 20 Turnpike Road Ucctboro, Passachusetts 01581 Centlemen:

Further infornation is now available to supplcracnt the THX sent to you by this office on Decenber 9,1971,'which infomed you of the failure of the relief valves on the secondary side of a steara ncncrotor of a prcosurized vator reactor. The cause of thic failure has now been detemined to be the failure to consider the reaction forces of discharn-in:; reldof valves in the design of the nozcles attaching the valyco to the header.

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( As a recult of this occurrence, several licenaces have conductc.d dynanic

'. strccc analycco of their cafety and relief valve installations. In oeveral casco, the analyses have indicated that the acrosses under certain

< - " ions vould be above those alloucd by code.

<.te.t of the significance and extent of this situation, you t:ny vish to re-evalucte the streca analysca for all caf ety and relief valvo insta.'in -

tions irmortant to nuc1ccr safety at your facility. Any re-evaluation should focus special attention on racchanical restraints and the assurptiens l used in the analyaca for safety and relief valvo installations uithin the prirary end secondary systcen.

Our acci3ned it.crector vill discuss your re-cvaluations with you during the nc::t inspection of your facility. -

t If you have any questienc cn this untter, vc will be pleased t.o discuss thcn with you.

I Very truly yours, THIS DOCUMENT CONTAINS i

' POOR QUAUTY PAGES-Jarce ?. O'Ecilly

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Director

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