The objective of this paper is to discuss recent lessons learned from the U.S. Nuclear Regulatory Commission's (NRC's) review of applications for license amendments in the structural engineering area from a regulatory perspective. The paper describes the Title 10 of the Code of Federal Regulations (10 CFR) Part 52, "Licenses, Certifications, and Approvals for Nuclear Power Plants," design-change process and makes recommendations for improving the quality of technical justifications supporting design changes. For a proposed design change, the paper discusses the need to adequately justify the proposal to ensure the safety of the revised design. The paper also emphasizes the importance of maintaining compliance with the standard design and the cited codes and standards during detailed design development and construction of Seismic Category I reinforced concrete and steel-concrete (SC) structures. The paper focuses on the role of critical sections, significance of Tier 2~* information (the asterisk is part of the expression) in design control documents (DCD), and implementation of the detailed design. Additionally, the paper makes recommendations for consideration by current and future new-reactor license applicants. This paper recommends the level of information needed to describe the methods of design for each structural element (wall, floor, frame, etc.) and to describe the design of the critical sections. The paper also discusses the prudence of a design certification (DC) applicant in considering a level of flexibility to account for construction realities such as materials availability and fabrication constraints.
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