Historical Context of Elevated Temperature Structural Integrity for Next Generation Plants: Regulatory Safety Issues in Structural Design Criteria of ASME Section III Subsection NH

Abstract

In 2006, ASME and DOE signed a cooperative agreement to update and expand appropriate materials, construction and design codes for application in future Generation IV nuclear reactor systems that operate at elevated temperatures. The second task in this ASME/DOE Gen-IV Materials Project was to identify issues relevant to ASME Section III, Subsection NH, and related Code Cases that must be resolved for licensing purposes for VHTGRs (Very High Temperature Gas Reactor concepts such as those of PBMR, Areva, and GA); and to identify the material models, design criteria, and analysis methods that need to be added to the ASME Code to cover the unresolved safety issues. The Nuclear Regulatory Commission (NRC) and Advisory Committee on Reactor Safeguards (ACRS) issues which were raised in 1983 in conjunction with the licensing of the Clinch River Breeder Reactor (CRBR) provide the best early indication of regulatory licensing issues for high temperature reactors. The approach to resolve the 25 identified elevated temperature structural integrity licensing issues was never implemented because Congress halted the construction of CRBR. This 1983 list provided the most definitive description of NRC elevated temperature structural integrity concerns. This paper presents both the results of the study by O’Donnell and Griffin [1] and a preliminary analysis by NRC staff of the earlier identified elevated temperature structural integrity issues that attempts to provide updated information for several of the next generation reactor types under consideration.