ML071560375

Letter to Alex Marion Transmitting Technical Basis Document and Results of Wolf Creek Scoping Study

ML071560375
Person / Time
Site:	Wolf Creek
Issue date:	06/20/2007
From:	Marilyn Evans NRC/NRR/ADES/DCI
To:	Marion A Nuclear Energy Institute
Sullivan E, NRR/DCI, 415-2796
Shared Package
ML071560363	List: ML071560375 ML071560385 ML071560398
References
Download: ML071560375 (3)

Text

June 20, 2007 Alex Marion, Executive Director Nuclear Energy Institute Nuclear Operations and Engineering 1776 I Street, N.W.

Washington, DC 20006-3708

Dear Mr. Marion,

In a February 14, 2007, letter from Jay Thayer, Nuclear Energy Institute (NEI) to J.E. Dyer, U.S. Nuclear Regulatory Commission (NRC), he proposed that industry perform advanced finite element fracture mechanics analyses to address NRC staff concerns that rupture could occur in pressurizer dissimilar metal nozzle welds without prior evidence of leakage (ML070600672).

Consistent with the project plan described in Mr. Thayers letter, on March 20, 2007 the Electric Power Research Institute provided results of the Phase I draft calculation to the Expert Review Panel for Advanced Finite Element Analysis (FEA) Crack Growth Calculations (ML070940229).

This calculation was performed by Dominion Engineering, Inc.

On April 4, 2007, I sent you a letter (ML070940186) to document NRC staff comments and concerns regarding the Phase I draft calculation. In the letter, I indicated that a technical basis document would be provided with additional information related to an NRC staff concern regarding the industrys approach for calculating crack stability. This NRC staff document was provided to the industry prior to the meeting held on this subject on April 9, 2007. Since that time, the technical basis document has been finalized. This letter serves to formally provide you with the final version of that document. The content and scope of the enclosure is essentially unchanged in content and scope from the earlier version.

The NRC staffs final report on the Wolf Creek pressurizer nozzle weld scoping study is also attached. Work on this document was begun in early November 2006, and it contains the results of the staffs scoping fracture mechanics analyses on the pressurizer nozzle weld flaws found at Wolf Creek. The NRC staff discussed the analyses that are documented in this report

A. Marion during public meetings that took place on November 30, 2006, and December 20, 2006, and during Advisory Committee on Reactor Safeguards (ACRS) meetings held on February 2, 2007, and March 6, 2007. A draft version of this report was provided to the ACRS and has since been updated to include the results of leakage calculations.

Sincerely,

/RA/

Michele G. Evans, Director Division of Component Integrity Office of Nuclear Reactor Regulation

Enclosures:

1. Technical Note on Critical Flaw Size Evaluations for Circumferential Cracks in Dissimilar Metal Welds

2. Evaluation of Circumferential Indications in Pressurizer Nozzle Dissimilar Metal Welds at the Wolf Creek Power Plant CC: A. Marion, NEI J. Thayer, NEI C. King, EPRI C. Harrington, EPRI D. Weakland, MRP J. Gasser, MRP D. Rudland, EMCC G. Wilkowski, EMCC

A. Marion during public meetings that took place on November 30, 2006, and December 20, 2006, and during Advisory Committee on Reactor Safeguards (ACRS) meetings held on February 2, 2007, and March 6, 2007. A draft version of this report was provided to the ACRS and has since been updated to include the results of leakage calculations.

Sincerely,

/RA/

Michele G. Evans, Director Division of Component Integrity Office of Nuclear Reactor Regulation

Enclosures:

1. Technical Note on Critical Flaw Size Evaluations for Circumferential Cracks in Dissimilar Metal Welds

2. Evaluation of Circumferential Indications in Pressurizer Nozzle Dissimilar Metal Welds at the Wolf Creek Power Plant CC: A. Marion, NEI J. Thayer, NEI C. King, EPRI C. Harrington, EPRI D. Weakland, MRP J. Gasser, MRP D. Rudland, EMCC G. Wilkowski, EMCC ADAMS Package Accession No.: ML071560363 OFFICE NRR/DCI NRRA/DCI NAME ESullivan MEvans DATE 06/ 8 /07 06/ 20 /07 OFFICIAL RECORD COPY