ML20211D351

Forwards Main Steam Bypass Sys Testing Program Rept, Preliminary Rept on Main Steam Bypass Piping Fatigue Analysis & Life Expectancy & Preliminary Steam Bypass Line Structural Evaluation

ML20211D351
Person / Time
Site:	Fermi
Issue date:	10/16/1986
From:	Agosti F DETROIT EDISON CO.
To:	Adensam E Office of Nuclear Reactor Regulation
Shared Package
ML20211D357	List: ML20211D351 ML20211D360 ML20211D396 ML20211D421
References
VP-86-0146, VP-86-146, NUDOCS 8610220177
Download: ML20211D351 (2)

Text

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$2.""eS$!If Nuclear Operations Detroit

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October 16, 1986 VP-86-0146 Office of Nuclear Reactor Regulation Ms. Elinor G. Adensam, Director Project Directorate No. 3 Division of BWR Licensing U. S. Nuclear Regulatory Commission Washington, D.C.

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Reference:

1)

Fermi 2 NRC Docket No. 50-341' NRC License No. NPF-43 2)

Detroit Edison to NRC Letter, " Service Life of Main' Steam Bypass Line",

VP-86-0097, dated July 22, 1986

Subject:

Service Life of Main Steam Bypass Line Reference 2 indicated that Detroit Edison would conduct a test program on the main steam bypass lines to obtain as-built performance data for use in evaluating the service life of the new bypass piping.

Analysis of this data using fracture mechanics methodology was performed by Hopper and Associates, l

indicating that the piping is acceptable if cumulative l

operation of each bypass line with bypass valve position l

between 30% and 40% opened does not exceed 130 days.

Based on l

this analysis, the new piping has a service life which will i

allow it to remain in service for the life of the plant under l

anticipated operating conditions.

Detroit Edison will maintain a record of the cumulative time the lines are operated in the high stress range.

This-time will be reported annually, and will not exceed a cumulative value of 100 days without prior notice.

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9 Ms. Elinor G. Adensam October 16, 1986 VP-86-0146 Page 2 However, fatigue analysis of the piping by Stone and Webster using different assumptions regarding the forcing function and the relative distribution of flexural and moment forces indicates that the operation of each line with bypass valve position between 30% and 45% opened is acceptable for at least 13 days.

Evaluation ~of this model identified its sensitivity to an assumption regarding stress concentration in a fitting (pipe elbow) in the west bypass line.

Detroit Edison and Stone and Webster agree that this assumption is conservative and that additional test data may demonstrate that the actual stress concentration is less than originally assumed by Stone and Webster, resulting in a less restrictive operating limit for the bypass lines.

Therefore, additional data will be taken during the startup test program.

This data will be evaluated and the results reported to you prior to exceeding 13 days of operation of the bypass lines in the 30% to 45% range for bypass valve position.

Additional detail regarding the analyses performed is provided in the attached report, which compares the methods and assumptions used.

This report also provides the basis for the additional testing to be performed.

If you have any questions on this matter, please contact Mr. J.

E. Conen, (313) 586-4275.

Sincerely

-4 0 E / b

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cc:

Mr. M. D. Lynch Mr. W. G.

Rogers USNRC Document Control Desk Washington, D. C.

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