ML20140E856

Advises That Util Proposes to Implement Controls to Ensure That Future Changes to Plant Maintain Seismic Ruggedness Subj to Controls Being Acceptable to NRC for Resolution of Seismic Issue.Criteria Will Be Flexible

ML20140E856
Person / Time
Site:	Maine Yankee
Issue date:	03/24/1986
From:	Whittier G Maine Yankee
To:	Thadani A Office of Nuclear Reactor Regulation
References
7348L-GDW, GDW-86-74, MN-86-45, NUDOCS 8603280214
Download: ML20140E856 (2)

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i MAME HARHEE ATOMMPOWER00MPARUe avaug,,Tl,,?n"eya's g (207) 623-3521 e

s March 24,1986 MN-86-45 GDW-86-74 Director of Nuclear Reactor Regulation United States Nuclear Regulatory Commission Washington, D. C. 20555 Attention: Mr. Ashok C. Thadani, Director PWR Project Directorate #8 Division of Licensing

References:

(a) License No. [PR-36 (Docket No. 50-309)

(b) M/APCo Letter to UNSRC dated March 14,1986 (MN-86-41)

Subject:

Seismic Review Program Gentlemen:

As indicated in Reference (b), Maine Yankee's Seismic Assessment Program has concluded that Maine Yankee's ceismic systems, structures and components possess seismic ruggedness well in excess of L9at inherent in the plant's original design basis. Maine Yankee proposes to implement controls to ensure that future changes to the plant maintain the seismic ruggedness of the plant, subject to these controls being acceptable to the NRC for resolution of the Maine Yankee seismic issue.

In performing future changes to the plant, Maine Yankee will ensure that the seismic ruggedness of existing structures, systems and components is maintained. New systems, and their associated structures and components will be designed to 0.18g NUREG-0098 50th percentile with SEP allowables (i.e., for piping, damping = 3% or PVRC, allowable stress = 2.4Sh , no OEE) up to any interface with existing structures, systems and components.

This criteria will have to be somewhat flexible in its application to interface b' atween new and existing systems. For example, a new system containing aumps, valves, piping, power supply, instrumentation, etc., will be designed to 0.18g as described above. However, equipment and structures that interface with, or are in the proximity of, the new system need not be upgraded above their existing seismic ruggeuness solely because of the installation of the new system.

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M AINE YANGEE ATOMIC POWER COMPANY United States Nuclear Regulatory Commission Page Two Attention: Mr. Ashok C. Thadini, Director MN-86-45 Please feel free to contact me if you have any questions in this matter.

Very truly yours, MAItE YANKEE ATOMIC POWER COWANY

).}b W G. D. Whittier, Manager Nuclear Engineering and Licensing GDW/bjp cc:-Dr. Thomas E. Murley Mr. Pat Sears Mr. Cornelius F. Holden ,

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