ML20058K616

Ro:On 740318,inadequate Design of Diesel Generator Air Starting Sys Piping Discovered.Corrective Actions:Addl Pipe Supports & Restraints Installed During Refueling Outage

ML20058K616
Person / Time
Site:	Monticello
Issue date:	04/16/1974
From:	Mayer L NORTHERN STATES POWER CO.
To:	Oleary J US ATOMIC ENERGY COMMISSION (AEC)
References
NUDOCS 9102120654
Download: ML20058K616 (1)

Text

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N Regulatory Docket File NM  ;

NORTHERN STATES POWER COMPANY M IN N E APO LI S. M I N N E SOTA 55401 April 16, 1974 f.- ,-

,4 y i ,P f~ 'l f ,s Mr. J F O' Leary, Director jg , t. g ;( ; -  :,

I; Directorate of Licensing

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Office of Regulation U S Atomic Energy Commission 'c Washington, DC 20545 s, .

Dear Mr. O' Leary:

MONTICELLO NUCLEAR GENERATING PLANT Docket No. 50-263 License No. DPR-22 Inadequate Design of Diesel Generator Air Starting System Pip!ng A condition has been discovered at the Monticello Nuclear Generating Plant which we are reporting to your office in accordance with Section 6.7.3.2, Unusual Events, of the Technical Specifications of Provisional Operating License DPR-22. 1 On March 18, 1974, it was determined that the stress on certain portions of the emergency diesel generator air starting system piping could exceed the design allowable stress during design basis earthquake conditions. This condition is contrary to the requirements for a Class I system as defined in Section 12.2 of the Final Safety Analysis Report.

Additional pipe supports and restraints are being installed during the present i refueling outage. The modified system will meet Class I requirements.

Yours very truly, A *

,p - 2 ,

L 0 Mayer, PE dQ/V, Director of Nuclear Support Services  %.

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LOM/kn ,

cc: J G Keppler  ;

G Charnoff Minnesota Pollution Control Agency Attn. E A Pryzina 9102120654 CF 740416 '

ADOCK 05000263 CF