scope:

Scope and Layout

This Guide is intended to facilitate the design of SC walls for safety-related nuclear facilities. The procedures outlined in this document are based on Supplement No. 1 to the AISC Specification for Safety-Related Steel Structures for Nuclear Facilities, ANSI/AISC N690 (AISC, 2015). Appendix N9, adopted into ANSI/AISC N690 as part of the Supplement, presents the requirements for the design of SC walls. Any reference to Appendix N9 in this Design Guide is referring to ANSI/AISC N690 Appendix N9. This Design Guide is to be used in conjunction with ANSI/AISC N690. The Design Guide:

• Addresses SC walls that meet the requirements of Appendix N9

• Provides supplementary recommendations for the design of modular SC structures using the provisions of Appendix N9

• Discusses the design of SC wall connections, including design philosophies and typical connection details

• Presents illustrations explaining the tolerance requirements for construction and fabrication of SC walls

This Design Guide provides primary procedural steps required for the design of SC structures. However, nuclear construction needs to satisfy other regulatory and environmental requirements, which may affect the design procedure. There may be project-specific scenarios that need to be considered in the design. The Design Guide may be used as a platform for the design of modular SC walls for nuclear construction.

This Design Guide discusses various aspects of the analysis and design of SC structures based on ANSI/AISC N690. The minimum requirements that an SC wall needs to meet in order for the provisions of Appendix N9 to be applicable are discussed. This Design Guide then discusses the detailing requirements for SC walls. These detailing requirements are provided to address specific SC limit states, such as faceplate local buckling. The requirements include faceplate slenderness requirements, and steel anchor and tie detailing. Guidelines for modeling and analysis of SC walls are presented. Additionally, the determination and basis of individual design strength equations will be presented. Interaction of demands is also discussed.

ANSI/AISC N690 provides procedural recommendations for the design of SC wall connections. This Design Guide addresses the design of connections in detail. Different connection philosophies, force transfer mechanisms, and types of connections are discussed with illustrations. The implementation of the provisions of ANSI/AISC N690 Appendix N9 is illustrated using a design example presented in Appendix A.

DESIGN EXAMPLE

This Design Guide provides a design example for an SC wall structure. An SC wall from a compartment of a typical safety-related nuclear facility is selected and all aspects of the design of that wall are discussed. The design example is presented in Appendix A. The example discusses the rationale for selecting the preliminary details of the structure. Discussion of the basis for the material selection is presented in the example. For brevity, the example does not present the details of the finite element analysis models, procedures, and results. Representative design demands are considered for design of the SC wall. The SC wall considered does not include any attachments or openings. The designed SC wall is not checked for impactive and impulsive loading in the example. It is considered that the fabrication and construction tolerances and quality assurance and control checks are performed during the erection of the SC wall.

The design of modular SC walls needs to consider constructability aspects, such as fabrication and erection issues. Based on transportation capabilities, the size of the prefabricated module is established. Specific analysis such as barge transportation analysis may need to be performed for submodules, based on the erection and fabrication sequencing, to consider the erection and fabrication loads, concrete casting pressure, and demands on ties and ribs prior to casting. Therefore, the designers need to be cognizant of the fabrication and erection procedures and sequence to ensure the design can be implemented without any issues. Appendix N9 provides fabrication and erection tolerances that need to be met for the provisions of Appendix A to be applicable. These tolerances are discussed in Section 13 of this Design Guide. While the design example presents the methodology for the design of modular SC walls, the designer needs to consider the constructability aspect of these walls during the analysis and detailing phases of the design.