ML20212K837

Requests Concurrence That Completion of Committed Mods Resolve long-standing Licensing Concern.Changes to Seismic Margins Program & Scheduled Completion Dates Listed

ML20212K837
Person / Time
Site:	Maine Yankee
Issue date:	02/26/1987
From:	Whittier G Maine Yankee
To:	Thadani A Office of Nuclear Reactor Regulation
References
8492L-GDW, GDW-87-43, MN-87-22, NUDOCS 8703090431
Download: ML20212K837 (2)

Text

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MAIRE HARHEE MGMIOPOWERComPARUe ,uaver,Ja?n"eCa"a'e (207) 623-3521 e

February 26, 1987 MN-87-22 GDH-87-43 Director of Nuclear Reactor Regulation United States Nuclear Regulatory Commission Hashington, D. C. 20555 Attention: Mr. Ashok C. Thadani, Director PHR Project Directorate #8 Division of Licensing

References:

(a) License No. DPR-36 (Docket No. 50-309)

(b) NRC to M.Y. letter dated (c) M.Y. to NRC letter dated

Subject:

Maine Yankee Seismic Margins Program Gentlemen:

For the past eight months, Maine Yankee has been working with the NRC staff and its consultants on a seismic margins program. This program, was designed to demonstrate the feasibility of the margin assessment methodology, and to resolve NRC staff concerns about the adequacy of Maine Yankee's seismic design. The program has been completed and a draft report issued.

The program has demonstrated that the Maine Yankee plant possesses seismic ruggedness well beyond the plant's original design. The program also identified several areas where the seismic ruggedness of the I ant cou!d be effectively enhanced.

The changes that we have decided to make along with the scheduled completion dates are listed below.

Description of Schedule Completion Change Date

• Diesel fuel day tank anchorage upgrade done

• Control Room cooler anchorage upgrade done

• Helding cart / gas bottle tiedown done

• Security lighting tiedown done

• Maine control board alarm tiedown done

• Strengthen blockwall VE 21-1 1987 Outage

• Upgrade anchors for fans 44A & B 1987 Outage

• Install internal anchors for transformers 507 & 608 1987 Outage

• Replace safety class batteries 1 & 3 1987 Outage

• Replace safety class batteries 2 & 4 1988 Outage

• Refueling water storage tank anchorage upgrade 1988 Outage O!

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MAINE YANKEE ATOMIC POWED COMPANY

' United States Nuclear Regulatory Ccanission Page Two Attention: Mr.- Ashok C. :Thadani, Director MN-87-22 The draft seismic margins report indicates that the Maine Yankee plant could. withstand seismic events well in excess'of the plant's original design basis without endangering public health and safety. The report also indicates that.the limiting component is the refueling water storage tank (RHST) with a

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higli confidence of low probability of failure (hcipf) of 0.21g. As indicated in the foregoing table, we plan to upgrade the seismic ruggedness of this  ;

tank, by improving its anchorage, no later then the 1988 refueling outage. He are making an effort to complete all or part of these upgrades during the 1987 refueling outage. Although the anchorage upgrades have not been finally designed, we expect to upgrade the tank's seismic ruggedness to a hcipf value

-in the. range of 0.27g.

He would appreciate your concurrence that completion of these committed modifications resolves this. long standing licensing concern so that we may

. apply our attention and resources to other~ safety enhancing efforts.

Very truly yours, MAINE YANKEE ATOMIC P0HER COMPANY blh'AV G. D. Hl.ittier, Manager Nuclear Engineering and Licensing

.G0H/bjp.

cc: Dr. Thomas E. Murley

Mr. Pat. Sears

Mr. Cornelius F. Holden i.

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