Civil Engineering Association

This Specification contains Load and Resistance Factor Design (LRFD) criteria for the design, fabrication, and erection of steel safety-related structures and structural elements for nuclear facilities. It is intended to be compatible with, and a supplement to, the 1999 AISC Load and Resistance Factor Design Specification for Structural Steel Buildings hereafter referred to as the AISC LRFD Specification. Unless stated otherwise, provisions of the AISC LRFD Specification are applicable. Only those sections that differ from the AISC LRFD Specification provisions are stated within this Specification. Section designations within this Specification are preceded by the letter N to denote nuclear facility design provisions. This specification includes the list of additional symbols, the glossary of additional definitions, and the appendices. Additional provisions for stainless steel sections are provided in Section NA5.3. Specifically excluded from this Specification are pressure retaining components, e.g., pressure vessels, valves, pumps, and piping. In the design of members and connections of Seismic Force Resisting Systems, the AISC Seismic Provisions for Structural Steel Buildings, in general, are not applicable. However, the detailing requirements of Sections 6 and 7 of the provisions shall be appropriately considered when designing for plastic analysis. Single angle members shall comply with the Load and Resistance Factor Design Specification for Single-Angle Members and with this Specification. Hollow structural sections (HSS) shall comply with the Load and Resistance Factor Design Specification for Steel Hollow Structural Sections and with this Specification. The sponsors of any system or construction within the scope of this Specification, the adequacy of which has been shown by successful use or by analysis or test, but which does not conform to or is not covered by this specification, shall have the right to present the data on which their design is based to the authority having jurisdiction for review and approval. Structures and structural elements subject to this Specification are those steel structures which are parts of a safety-related system or which support, house, or protect safety-related systems or components, the failure of which would impair the safety-related functions of these systems or components. Safety categorization for nuclear facility steel structures and structural elements shall be the responsibility of the owner. As used in this Specification, the term structural steel refers to the steel elements of the structural steel frame essential to the support of the required loads. Such elements are enumerated in Section 2.1 of the AISC Code of Standard Practice for Steel Buildings and Bridges. For the design of cold-formed steel structural members, whose profiles contain rounded corners and slender flat elements, the provisions of the American Iron and Steel Institute North American Specification for the Design of Cold-Formed Steel Structural Members shall be applicable.

The Specification for Safety-Related Steel Structures in Nuclear Facilities, hereafter referred to as the Nuclear Specification, shall apply to the design of safetyrelated
steel structures and steel elements in nuclear facilities. The Chapter, Appendix, and Section designations within the Nuclear Specification are preceded by letter N to denote nuclear facility provisions. The Nuclear Specification is compatible with the AISC Specification for Structural Steel Buildings (ANSI/AISC 360), hereafter referred to as the Specification. Provisions of the Specification are applicable unless stated otherwise. Only those sections that differ from the Specification provisions are indicated in the Nuclear Specification. The Nuclear Specification includes the list of additional symbols, additional glossary terms, Chapters NA through NM, and Appendices N1 through N7. The commentary and user notes (interspersed throughout the specification) are not part of the specification. User Note: User notes are intended to provide concise and practical guidance in the application of the provisions. The steel elements shall be as defined in the AISC Code of Standard Practice for Steel Buildings and Bridges, Section 2.1. Structures and structural elements subject to the Nuclear Specification are those steel structures that are part of a safety-related system or that support, house, or protect safety-related systems or components, the failure of which would impair the safety-related functions of these systems or components. Safety categorization for nuclear facility steel structures and structural elements shall be the responsibility of the owner. Specifically excluded from the Nuclear Specification are the pressure-retaining components, for example, pressure vessels, valves, pumps, and piping. In the design of members and connections of seismic load resisting systems, the AISC Seismic Provisions for Structural Steel Buildings (ANSI/AISC 341), in general, are not applicable. However, the detailing requirements of Sections 6 and 7 of the Seismic Provisions shall be appropriately considered when designing for inelastic behavior. The sponsors of any structural system or construction within the scope of the Nuclear Specification, the adequacy of which has been shown by successful use or by analysis or test, but which does not conform to or is not covered by the Nuclear Specification, shall have the right to present the data on which their design is based to the authority having jurisdiction for review and approval. User Note: For the design of structural members, other than hollow structural sections (HSS), that are cold-formed to shapes with elements not more than 1 in. (25 mm) in thickness, the use of provisions of the AISI North American Specification for the Design of Cold-Formed Steel Structural Members is recommended, incorporating the loads and load combinations delineated in Section NB2 of the Nuclear Specification.