PY-CEI-NRR-2384, Provides Supplemental Info Re 990325 Request for Approval of Repair Plan for Feedwater Nozzle to safe-end Weld. Clarification Provided on Listed Three Items,Per 990329 Telcon with NRC

Provides Supplemental Info Re 990325 Request for Approval of Repair Plan for Feedwater Nozzle to safe-end Weld. Clarification Provided on Listed Three Items,Per 990329 Telcon with NRC

ML20205F955
Person / Time
Site:	Perry
Issue date:	04/01/1999
From:	Myers L CENTERIOR ENERGY
To:	NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM)
References
PY-CEI-NRR-2384, NUDOCS 9904070068
Download: ML20205F955 (2)

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Lew W. Myers 440-280-59I5

' Vht President Far 440-280-8029 April 1,1999 l PY-CEl/NRR-2384L United States Nuclear Regulatory Commission Document Control Desk Washington, DC 20555 Perry Nuclear Power Plant Docket No. 50-440 Supplemental information in Support of Request for Approval of Feedwater Nozzle Repeir Plan -

Ladies and Gentlemen:

This letter supplements the March 25,1999, letter (PY-CEl/NRR-2380L) submitted by the Perry Nuclear Power Plant (PNPP) staff, which requested approval of a repair plan for a feedwater nozzle to safe-end weld. The proposed repair consists of performing a full structural weld overlay to repair a reported flaw in the N4C-KB feedwater nozzle to safe-end weld.

On Monday, March 29,1999, the PNPP staff participated in a telephone conference call with NRC staff to discuss the proposed weld overlay repair plan. The NRC staff revested that clarification be provided on three issues. To support the NRC's request, the following clarification is provided.

Issue 1 Provide clarification that the proposed repair method is considered an attemative to an Dj approved American Society of Mechanical Engineers (ASME) Boiler and Pressure Vessel Code repair.

The proposed repair consists of a modified weld overlay that represents an attemative to a standard ASME Section XI Code repair, which would involve removal of the defect.

The proposed repair is a modification of ASME Section XI Weld Overlay Code Case N-504. This Code Case allows a weld overlay repair of an austenitic stainless weld joint using austenitic stainless steel filler. The proposed repair involves a carbon steel to low alloy steel dissimilar weld metaljoint and uses Alloy 52 (nickel alloy) fiiler. The proposed weld overlay repair provides a full structural replacement of the underlying weld joint and is performed in accordance with all design and inspection requirements of ASME Code Case N-504. Therefore, the only exception to ASME Code Case N-504 involves the materials. However,'sinca the filler material, Alloy 52, is highly resistant to Intergranular Stress Corrosion Cracking (IGSCC) and the carbon steel safe-end is highly resistant to environmentally assisted cracking, the proposed attemative to ASME Code Case N-504 gq}

is justified for the weld overlay.

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April 1,1999 Page 2bf 2 Issue 2 Provide clarification on the specific material content of the safe-end and its relation to the

- proposed temper bead method.

The safe-end associated with weld N4C-KB is SA-508, Class 1, (P1, Group 2) material.

The Certified Material Test Report for this safe-end shows the carbon content is 0.23%.

Since the carbon content is relatively low, the ability to harden the material by applying a welded structural overlay is also low. A temper bead weld overlay is not required for the proposed wald repair. However, as a conservative approach, a customized temper bead weld overlay will be performed and a weld procedure to support this method has been qualified. Special precautions have been taken for bead placement during the first three layers to ensure a high quality overlay. These precautions were used during procedure qualification and are incorporated into the welding procedure specification that will be used for the weld overlay.

Issue 3 i

Provide clarification on the ASME Code acceptance criteria for the lamination inspection.

i As the weld overlay repair is not a prescribed ASME Section 111 or ASME Section XI repair, EPRI-NP-4720-LD, " Examination of Weld-Overlaid Pipe Joints", provides l guidelines for the application of ASME Section lit er ASME Section XI acceptance criteria. As an attemative to ASME Section lil, the acceptance criteria of ASME Section XI will be applied for the weld overlay famination inspection. Flaws will be characterized in accordance with ASME IWA-3300. In particular, planar indications oriented within 10 degrees of a plane parallel to the surface of the overlay will be considered laminar flaws.

For those flaws that are characterized as laminar flaws, the acceptance criteria of ASME Table IWB-3514-3, " Allowable Laminar Flaws", will be used, and will be based on the overlay thickness.

If you have questions or require additional information regarding the proposed N4C-KB nozzle to safe-end weld repair plan, please contact Mr. Henry L. Hegrat, Manager - Regulatory Affairs, at (440) 280-5606.

Very truly yours, Y

cc: NRC Project Manager NRC Resident inspector NRC Region lli