ML20087N108

Final Deficiency Rept 84-11 Re RHR HX Support Bracing. Initially Reported on 840217.Bracing Details Added to Design Drawings & Drawings Released for Const

ML20087N108
Person / Time
Site:	Nine Mile Point
Issue date:	03/19/1984
From:	Mangan C NIAGARA MOHAWK POWER CORP.
To:	Starostecki R NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION I)
References
84-11, NMP2L-011, NMP2L-11, NUDOCS 8404030113
Download: ML20087N108 (2)

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i M Y NIAGARA RUMOHAWK NIAGARA MOHAWK POWER CORPORATION /300 ERIE BOULEVARD WEST. SYRACUSE, N Y 13202/ TELEPHONE (315) 4741511 March 19, 1984 (NMP2L011)

Mr. R. W. Starostecki, Director U.S. Nuclear Regulatory Commission Region I Division of Project and Resident Programs 631 Park Avenue King of Prussia, PA 19406 Re: Nine Mile Point Unit 2 Docket No. 50-410

Dear Mr. Starostecki:

Enclosed is a final report in accordance with 10CFR50.55(e) for the problem concerning RHR heat exchanger support bracing (55(e)-84-ll). This problem was reported via telecon to S. Collins of your staff on February 17, 1984.

Very truly yours, bMbNh C. V. Mangar t

Vice Preside"nt Nuclear Engineering & Licensing

-CVM/TL:ja Enclosure xc: Director of Inspection and Enforcement

,0.S. Nuclear Regulatory Commission Washington, DC 20555 R. Gramm (NRC Resident Inspector) 8404030113 840319 $

, PDR ADOCK 05000410 P S PDR h i@

O NIAGARA M0 HAWK POWER CORPORATION ,

NINE MILE POINT - UNIT 2 DOCKET NO. 50-410 Final Report for a Problem Concerning RHR Heat Exchanger Support Bracing (55(e) 111 Description of -the-Problem The structural analysis and design of the Residual Heat Removal heat exchanger supports included horizontal braces at the upper restraint level, but the bracing details were not transferred onto the design drawings. These heat exchangers are located in the north and south auxiliary bays of the reactor building.

Analysis of Safety-Implications The omission of horizontal braces could result in an increase in stresses in the heat exchanger or its supports. The increase of stresses beyond a certain level could adversely affect the intended function of the heat exchangers. 'An analysis to determine the extent of the increase in stresses in the heat exchanger and/or its supports was not made. However, the corrective action as outlined below has been taken.

Corrective Action The bracing details have since been added to the design drawings and the drawings have been released for construction.

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