BVY-94-125, Submits Insp Plan,Including Plans for Evaluation &/Or Repair of Plant Core Shroud Based on Insp Results in Accordance W/ Commitment Made in 940817 Response to GL 94-03

Submits Insp Plan,Including Plans for Evaluation &/Or Repair of Plant Core Shroud Based on Insp Results in Accordance W/ Commitment Made in 940817 Response to GL 94-03

ML20078Q425
Person / Time
Site:	Vermont Yankee
Issue date:	12/15/1994
From:	Pelletier J VERMONT YANKEE NUCLEAR POWER CORP.
To:	NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM)
References
BVY-94-125, GL-94-03, GL-94-3, NUDOCS 9412220168
Download: ML20078Q425 (2)

Text

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' VERMONT YANKEE NUCLEAR POWER CORPORATION

.- Ferry Road, Brattleboro, VT 05301-7002 g ENGINE R N OFFICE 580 MAIN STREET

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BOLTON, MA 01740 (508) 779-6711 December .15,1994 BVY 94-125 United States Nuclear Regulatory Commission ATTN: Document Control Desk Washington, DC 20555

References:

a) License No. DPR-28 (Docket No. 50-271) b) USNRC Generic Letter 94-03, "Intergrannular Stress Corrosion L Cracking of Core Shrouds in Boiling Water Reactors," dated July 25,1994 c) Letter, BWROG to USNRC, " Response to NRC Request for Shroud Information," dated July 13,1994 d) Letter, BWROG to USNRC, " Revision 1 to BWROG Shroud Document," dated August 5,1994 e) Letter BVY 94-82, VY to USNRC, " Response to USNRC Generic Letter 94-03," dated August 17,1994 l

Subject:

Vermont Yankee Plans to inspect the Core Shroud Circumferential t

Wolds During the Spring 1995 Refueling Outage The purpose of this letter is to submit an inspection plan, including plans for evaluation and/or repair of the Vermont Yankee core shroud based on inspection results in accordance with our previous commitment, [ Reference (e)).

Vermont Yankee is scheduled to be shut down for a refueling and maintenance outage starting March 18,1995 and will perform an inspection of the core shroud circumferential L welds during the outage.

inspections will be performed from the outside diameter of the shroud using Ultrasonic Detection (UT) techniques to assess the structural integrity of the circumferential welds. The t technique will be equal to or better than that assessed in the BWROG VIP (Vessel Internals -

Program) Core Shroud NDE and Uncertainty Document.

The inspection scope (weld coverage) will be consistent with the BWROG VIP draft documents in that all areas reasonably accessible to the remote scanner will be examined.

j If interferences are encountered, reasonable attempts will be made to reposition the scanner l and continue inspecting. Based upon access studies and drawing reviews, it is projected that over 50% of each weld will be accessible for examination by UT.

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9412220168 941215 PDR ADOCK 05000271 hI Oq

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VERMONT YANKEE NUCLEAR POWER CORPORATION United States Nuclear Regulatory Commission December 15,1994 Page 2 .

If the cumulative length of each weld inspected by UT is less than 50% of the weld length, then supplemental visual inspections will be performed of that weld. If visualinspection (VT) techniques are performed to supplement the UT inspections, the VTs will be performed from both the ID and OD to provide the necessary quantitative assessment of the weld (s).

Supplemental inspections will continue until inspection of at least 50% (UT plus VT) of the total weld length of each weld is achieved. If at least 50% weld length inspection cannot be achieved, all reasonably accessible areas for that weld will be examined using these techniques.

Flaw evaluations will be performed using the limit load analysis techniques of the ASME Code, as endorsed by the BWROG VIP. Vermont Yankee is in the process of havirig updated seismic analysis of the core shroud performed to obtain weld specific forces and moments, in addition, we are supporting the BWROG VIP project to develop grouping analyses to obtain LOCA and Main Steam Line Break forces and moments. These loads will be used to calculate stresses in each shroud weld. Limit load analysis is the appropriate technique for Vermont Yankee since the end of life peak fluence on the core shroud is predicted to be 2.7E20 n/cm 2, As stated in Reference (e), inspection results and flaw evaluation results will be forwarded to NRC within 30 days following completion of the inspections and evaluation of the data.

We trust this letter provides the necessary information describing our plans for inspection and evaluation of our shroud. Should you need additional information, please contact us.

Sincerely, VERMONT YANKEE NUCLEAR POWER CORP.

7 James P. Pelletier Vice President, Engineering cc: USNRC Region i Administrator USNRC Resident inspector - VYNPS / [N' kh b*

USNRC Project Manager - VYNPS 7"~~'

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STATE OF VERMONT ) i WINDHAM COUNTY k Then personally appeared before trze, James P. Pelletier, who, being duly sworn, did state that he is Vit't?fesiden Y/

Engineering, of Vermont Yankee Nuclear Power Corporation, that he is duly authorized to execute and file the foregoing do u '

in the name and on the behalf of Vermont Yankee Nuclear Power Corporation, and that the statements thereinjnre t(pe)f . st his knowledge and belief. N.m bl/

Gila M. Fontaine, N'otary Public My Commission expires February 10,1995

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