ML20148H904

Responds to NRC Bulletin 88-002, Rapid Propagating Fatigue Cracks in Steam Generator Tubes. Detailed Methodology & Results of Analysis Will Be Submitted by 880901

ML20148H904
Person / Time
Site:	Yankee Rowe
Issue date:	03/25/1988
From:	Devincentis J YANKEE ATOMIC ELECTRIC CO.
To:	NRC OFFICE OF ADMINISTRATION & RESOURCES MANAGEMENT (ARM)
References
FYR-88-40, IEB-88-002, IEB-88-2, NUDOCS 8803300114
Download: ML20148H904 (2)

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• Tsttphons (617) 872-6100 TWX 710-380 7319 YANKEE ATOMIC ELECTRIC COMPANY y~

1671 Worcester Road, Framingham, Massachusetts 01701

_e March 25, 1988 FYR 88-40 United States Nuclear Regulatory Commission Document Control Desk Washington, DC 20555

References:

(a) License No. DPR-3 (Docket No. 50-29)

(b) USNRC Bulletin 88-02: Rapidly Propagating Fatigue Cracks In Steam Generator Tubes, dated February 5, 1988 (c) YAEC Letter to USNRC, dated June 24, 1985

Dear Sir:

The purpose of this letter is to provide our response to NRC Bulletin 88-02.

Bulletin Action A: Inspection of Eddy Current Data As requested by the bulletin, Yankee Atomic Electric Company (YAEC) has evaluated the eddy current data from the most recent (1987) steam generator inspection. The 1987 Inspection Plan included a full length bobbin coil inspection (tube end-to-tube end) of 1,507 tubes in the No. 2 steam generator. Eddy current data from a total of 380 tubes from the No. 2 steam generator were re-examined for evidence of clamping at the uppermost tube support plate.

All locations examined at the upper tube-to-tube support plate show evidence of deposits on the outside of the tubes, however, no physical distortion of the tubes was found. This was expected because the stainless steel tube material used at YNPS has never exhibited physical distortion.

The eddy current results were also reviewed to determine the location of the Anti-Vibration Bar (AVB). The tubes sampled are in Rows 5 through 10 with several outer rows evaluated to determine the AVB profile. The AVB penetrates to Row 8 with complete coverage. Approximately one half of Row 7 is supported by the AVB. The AVB profile is unknown for Column 1 which is inaccessible due to the configuration of the eddy current probe manipulator.

0114 DR DOCW a \

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.g :D United States Nuclear Regulatory Comission March 25, 1988 Page 2 FYR 88-40 Bulletin Action C: Implementation of Leak Rate Monitoring Program As required by Bulletin 88-02, YAEC has implemented an enhanced Primary-to-Secondary Leak Rate Monitoring Program as an interim compensatory measure within the time limit requested.

Schedule of Future Submittal This letter has provided the required information for imediate actions in accordance with Bulletin 88-02. We plan to submit the detailed methodology and results of analysis by September 1, 1988.

If there are any questions regarding this matter, please call.

Very truly yours, YANKEE ATOMIC ELECTRIC COMPANY w j$

John DeVincentis Vice President 25.493 COMMONWEALTH OF MASSACHUSETTS)

)ss MIDDLESEX COUNTY )

Then personally appeared before me, J. DeVincentis, who, being duly sworn, did state that he is Vice President of Yankee Atomic Electric Company, that he is duly authorized to execute and file the foregoing document in the name and on the behalf of Yankee Atomic Electric Company and that the statements therein are true to the best of his knowledge and belief.

f x Nobert H. Groce Notary Public My Comission Expires August 29, 1991 cc: USNRC Region i USNRC Resident Inspector W. T. Russell, Regional Administrator - USh7C Region 1