Proposed Final Regulatory Guide DG-1093, "Guidance and Examples for Identifying 10 CFR 50.2 Design Bases"

September 12, 2000

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

Dear Dr. Travers:


During the 475th meeting of the Advisory Committee on Reactor Safeguards, August 29 - September 1, 2000, we met with representatives of the NRC staff and the Nuclear Energy Institute (NEI) to discuss proposed final Regulatory Guide DG-1093 regarding design bases information. This guide endorses Appendix B of NEI 97-04, "Design Bases Program Guidelines," as an acceptable method of meeting NRC requirements. We also had the benefit of the documents referenced.


We recommend issuance of DG-1093, which endorses NEI 97-04, Appendix B.


The term "design bases" is defined in 10 CFR 50.2 and is used in several regulations in 10 CFR Part 50, including 50.34, 50.59, Appendix A, and Appendix B. In recent years, there has been disagreement between the staff and the industry on the meaning of the 10 CFR 50.2 definition. The industry effort to resolve this disagreement began with proposed guidance and examples in 1997. The NEI guidance was developed as a result of system-specific engineering inspections that showed that some licensees were not maintaining design bases information as required by NRC regulations. In response to the problems identified during these inspections and other problems identified by the licensees, many licensees initiated design bases reconstitution programs. These programs sought to identify and selectively regenerate missing documentation. During the documentation effort, it became clear that the definitions of what constituted design bases information differed from licensee to licensee. The lessons learned from events at Millstone and Maine Yankee showed that the definition of design bases should be clarified.

The ACRS briefings in October and November 1999 provided a forum for discussion of this issue. The draft regulatory guide was published for comment in April 2000. NRC staff and NEI representatives have held numerous meetings to discuss the changes necessary to Appendix B of NEI 97-04 as a result of public comments received on the draft regulatory guide and to discuss additional changes proposed by the NRC staff in a letter to NEI dated July 18, 2000. The proposed final regulatory guide provides clarification of what constitutes design bases information.

We commend the staff and NEI for the completion of this difficult task through the extensive public meetings held with stakeholders in the past year.


Dana A. Powers


1.   Memorandum from D. B. Matthews, Office of Nuclear Reactor Regulation, NRC, to J. T. Larkins, ACRS, Subject: Final Regulatory Guide, "Guidance and Examples for Identifying 10 CFR 50.2 Design Bases," August 7, 2000.
2. Memorandum from S. L. Magruder, Office of Nuclear Reactor Regulation, NRC, to C. A. Carpenter, Office of Nuclear Reactor Regulation, Subject: Summary of July 27, 2000 Meeting with NEI on Revision to NEI 97-04 on the Definition of 10 CFR 50.2 Design Bases, July 31, 2000.

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