scope:

SCOPE AND GENERAL REQUIREMENTS

ASPECTS OF CONSTRUCTION COVERED BY THESE RULES

(a) Subsection NF contains rules for the material, design, fabrication, examination, installation, and preparation of certification documents (Certificate of Compliance and NS-1 Certificate of Conformance) for supports for components and piping which are intended to conform to the requirements for Class 1, 2, 3, and MC construction as set forth in Subsections NB, NC, ND, and NE, respectively, of this Section.

(b) They do not cover deterioration that may occur in service as a result of corrosion, erosion, radiation effects, or metallurgical instability of the materials (NCA-1130).

(c) Nuclear power plant supports¹ for which the rules are specified in this Subsection are those metal elements which transmit loads between components (NCA-1210), including piping systems, and intervening elements and the building structure. However, the term supports does not encompass a structural element the sole function of which is to carry dynamic loads caused by a postulated loss of pressure retaining integrity.

(d) The Owner shall be responsible for assuring the adequacy of the building structure and all intervening elements in the support load path in accordance with the requirements of NCA-3240 and NCA-3250. To the extent necessary, the support designer shall consider the structural interaction with intervening elements and the building structure.

(e) Except for the requirements listed in NF-1110(e)(1) through (e)(10), the requirements of Subsection NF do not apply to bearings, bushings, gaskets, hydraulic fluids, seals, shims, slide plates, retaining rings, wear shoes, springs, washers, wire rope, compression spring end plates, thread locking devices, cotter pins, sight glass assemblies, spring hanger travel and hydro stops, nameplates, nameplate attachment devices, or for compression dynamic stops used as stops² for seismic and other dynamic loads that are designed primarily for compressive loading and are not connected to the support or pressure boundary.

(1) The material of the exempt items shall be selected to tolerate the environmental conditions to which they will be exposed, such as temperature, fluids, humidity, and irradiation.

(2) The exempt item shall be designed for the loading conditions and other requirements identified in the Design Specification.

(3) Design Output Documents (NCA-3550) shall indicate items that are exempt.

(4) Materials, fabrication, and installation of the exempt items shall comply with Design Output Documents.

(5) Class 1 springs shall be inspected in accordance with NF-2520.

(6) Washers shall comply with the requirements of NF-4700.

(7) Wire rope shall comply with the requirements of NF-2530 and Article NF-3000.

(8) Compression spring end plates shall comply with the requirements of Articles NF-3000, NF-4000, NF-5000, and NF-8000.

(9) Compression dynamic stops shall comply with the requirements of Articles NF-3000, NF-4000, NF-5000, and NF-8000.

(10) Thread locking devices shall comply with the requirements of NF-4725.1.

¹ NCA-9200 provides the definition of "support" and other terms.

² Stops do not include snubbers and dampers (NF-3412.4).

RULES FOR SUPPORTS AND THEIR CLASSIFICATION

Rules for Supports

The rules of Subsection NF provide requirements for new construction and include consideration of mechanical stresses and effects which result from the constraint of free-end displacements and anchor point motions defined in NF-3121.12 and NF-3121.13, but not thermal or peak stresses.

Classification of Supports

Supports shall be constructed to the requirements of this Subsection that are applicable to the class of the component, including piping system, they are intended to support. Supports may be optionally classified as permitted in NCA-2134. When the components are optionally classified to a higher class as permitted in NCA-2134(d), the support need not be classified to the higher class.

BOUNDARIES OF JURISDICTION

Boundary Between Components and Supports

The jurisdictional boundary between components, including piping systems, and supports shall meet the requirements of NB-1132, NC-1132, ND-1132, or NE-1132 as applicable to the class of component.

Boundary Between Supports and the Building Structure

(a) Supports may bear on or may be welded, bolted, pinned, or clamped to the building structure. Typical examples of jurisdictional boundaries defined between supports and building structures are shown in Figs. NF-1132-1 and NF-1132-2.

(b) The jurisdictional boundary between a support and the load carrying building structure is the surface of the building structure.

(c) For the purpose of defining the jurisdictional boundary between a support and the building structure, structural members shown on the civil /structural drawings of the plant and considered in the building structural analysis may be designated building structure even though located in the support load path. However, structural members, except as defined in NF-1132(d), detailed on support drawings which are installed and used for the primary purpose of supporting piping or components shall be designated supports and be constructed to the rules of this Subsection.

(d) Surface mounted base plates, with or without grouting; fully or partially embedded steel elements intended to receive loads transmitted by supports; concrete anchors; and holddown bolts, nuts, and washers shall be designated building structure.

(e) If the means by which the support is connected to the building structure is a weld, the weld shall fall within the jurisdiction of this Subsection.

(f) If the means by which the support is connected to the building structure is a bolted joint to a building structural steel member, the bolts shall fall within the jurisdiction of this Subsection.

Boundary Between Supports and Intervening Elements

The jurisdictional boundary between supports and intervening elements in the support load path is the surface of the intervening elements. Supports may bear on or may be welded, bolted, pinned, or clamped to intervening elements. The means by which supports are connected to intervening elements shall fall within the jurisdiction of this Subsection.