Differing Professional Opinion on Steam Generator Tube Integrity

February 1, 2001

Dr. William D. Travers
Executive Director for Operations
U.S. Nuclear Regulatory Commission
Washington, D. C. 20555-0001

Dear Dr. Travers:

Subject: DIFFERING PROFESSIONAL OPINION ON STEAM GENERATOR TUBE INTEGRITY

In a memorandum dated July 20, 2000, you requested that the ACRS examine the technical issues associated with a differing professional opinion (DPO) on steam generator tube integrity. Specifically, you requested that the ACRS function as the equivalent of an Ad Hoc panel, under Management Directive 10.159, to review the DPO issues and provide you with a summary report documenting the conclusions and any recommendations relative to the pertinent technical issues.

In a memorandum dated September 11, 2000, we informed you of the establishment of an Ad Hoc Subcommittee that would function under the provisions of the Federal Advisory Committee Act, to review the technical merits of the DPO issues and develop proposed positions for consideration by the full committee. The Ad Hoc Subcommittee was composed of ACRS members D. A. Powers (Chairman), M. V. Bonaca, J. D. Sieber and T. S. Kress, and R. G. Ballinger from the Massachusetts Institute of Technology. The Subcommittee was supported by three consultants hired by the staff: I. Catton, University of California at Los Angeles, J. C. Higgins, Brookhaven National Laboratory, and R. E. Ricker, National Institute of Standards and Technology.

During its meeting on October 10-14, 2000, the Ad Hoc Subcommittee met with J. Hopenfeld, the DPO author, Professional Engineer R. A. Spence of the staff, and several other members of the NRC staff to discuss the DPO author's contentions and the staff's responses. To support its review, the Subcommittee and its consultants reviewed a large volume of documents, including those referenced in the Subcommittee's report.

Based on its discussion of the DPO author's contentions and the associated NRC staff's responses, the Subcommittee developed a NUREG report documenting its conclusions and recommendations, along with the bases for arriving at these conclusions and recommendations. This report was reviewed by the members of ACRS and the consultants to the Ad Hoc Subcommittee.

During the 478^th meeting, December 6-9, 2000, the ACRS reviewed the conclusions and recommendations of the Ad Hoc Subcommittee. The ACRS also discussed the DPO issues during its 477^th meeting, November 2-4, 2000. During this review, the Committee had the benefit of discussions with the DPO author and representatives of the NRC staff. The ACRS also had the benefit of the documents referenced in the attached report of the Ad Hoc Subcommittee.

The ACRS endorses the Ad Hoc Subcommittee's conclusions and recommendations included in its report, which is being sent to you with this letter for use in resolving the DPO issues. The ACRS would like to be kept informed of the resolution of the DPO issues.

Dr. William J. Shack did not participate in the Committee's deliberations regarding this matter.

	Sincerely,
	/RA/
	D. A. Powers Chairman, Ad Hoc Subcommittee

Enclosure:

• NUREG-[1740], "Voltage-Based Alternative Repair Criteria," a Report to the Advisory Committee on Reactor Safeguards by the Ad Hoc Subcommittee on Differing Professional Opinion, February 2001.
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