This work was supported by the United States Nuclear Regulatory Commission (NRC) through the Component Integrity Branch of the Division of Engineering of the Office of Nuclear Regulatory Research under several different contracts. Battelle Memorial Institute support was provided under NRC Contract NRC-04-02-074 (NRC Job Code Y6538). Mr. William Galyean of Idaho National Engineering Environmental Laboratory was supported under NRC Job Code Y6332. Dr. Cory Atwood was supported under NRC Job Code Y6492. Dr. Alan Brothers was supported under NRC Job Code Y6604.

The authors would first like to thank the members of the expert elicitation panel whose insights formed the basis for the results and conclusions reached in this report. The elicitation panel members also provided valuable editorial and technical comments that have been incorporated into this summary document. The panel members included:

Westinghouse Electric Co. LLC OJV Consultancy Limited Exelon Nuclear

Idaho National Engineering Environmental Laboratory Swedish Nuclear Power Inspectorate Engineering Mechanics Technology, Inc.

ERIN® Engineering and Research, Inc.

Structural Integrity Associates, Inc.

Gesellschaft fur Reaktorsicherheit (GRS) mbh Formerly GE Nuclear Energy/Now XGEN Engineering Pacific Northwest National Laboratory Engineering Mechanics Corporation of Columbus

A special debt of gratitude is expressed to the base case team members (Dr. David Harris, Mr. Bengt Lydell, Mr. William Galyean, and Dr. Peter Riccardella) for the extra effort they provided to conduct the base case and sensitivity analyses discussed in Sections 3 and 4 of this report. In addition, Dr. Riccardella provided base case frequencies for a series of non-piping components and Mssrs. Galyean and Lydell developed the non-piping precursor database. Summaries of the base case team members’ analyses are contained in Appendices D — I. Each appendix has been written by the responsible base case team member and these contributions are much appreciated and are vital to the technical basis of this NUREG. Mr. Lydell and Dr. Harris also tirelessly discussed and corrected the authors’ characterization of their efforts for accuracy and clarity.

The authors would also like to recognize the facilitation team members who assisted with the development of the technical issues and associated elicitation questions and who also participated in the individual elicitations sessions. Along with the authors, Dr. Ken Jacquay of Casco Services, Inc. was a principal member of the facilitation team

The authors are also appreciative of Dr. Corwin Atwood of Statwood Consulting and Dr. Alan Brothers of Pacific Northwest National Laboratory, who provided an external peer review of the elicitation
approach and analysis of results. They suggested a number of sensitivity studies to further validate and clarify the conclusions reached in this report. They also provided many helpful comments that have been used to clarify this report. Dr. Atwood, in particular, provided many valuable insights which were used to develop and refine the techniques used to analyze the elicitation results.

Many NRC staff also provided valuable comments and contributions that were used to revise the draft report, including Dr. Arthur Buslik, Mr. Stephen Dinsmore, Mr. Gary Hammer, Mr. Glenn Kelly, and Mr. Arthur Salomon,. In particular, the authors would like to thank Dr. Arthur Buslik for his contribution to Section 5.6.4.4 and Mr. Arthur Salomon for his reviewing and editing assistance. The authors are also grateful to Dr. David Rudland of Engineering Mechanics Corporation of Columbus for assisting with selected Monte Carlo calculations to evaluate the analysis of individual panelist responses.

Finally, the authors would like to thank Dr. Al Csontos of the NRC, who served as the program manager over the final months of this program, and to Ms. Charlotte Matthews and Ms. Patricia Zaluski, both of Battelle-Columbus, for their invaluable assistance in the preparation of this report.