Document: NRC Regulatory Guide
Document ID: 2e29f931-cdf2-4faa-a9e4-5d7cb237e57f
Document Type: regulatory_guide
Title: Service Limits and Loading Combinations for Class 1 Plate-and-Shell-Type Component Supports + HISTORY – HISTORY 10/2006 – DG-1169 , Proposed Revision 2
Source: NRC Regulatory Guide Division 1
Source URL: https://www.nrc.gov/docs/ML0630/ML063000484.pdf
Revision Date: 2023-06
Chapter: 
Section ID: RG-1.130
CFR Part: 
CFR Title: 

Content:
ecause large deformations can significantly change the stress distribution in the support system and its supported components. To provide a consistent level of safety, the ASME Code classification for component supports should, as a minimum, be the same as that of the supported components. This guide delineates levels of service limits and loading combinations, as well as supplementary criteria, for Class 1 plate-and-shell-type component supports, as defined by NF-1212 of Section III of the ASME Code. This guide does not address snubbers. Subsection NF of Section III permits the use of three methods for the design of Class 1 plate-and-shell-type component supports: (1) linear-elastic analysis, (2) load rating, and (3) experimental stress analysis. For each method, the ASME Code delineates allowable stress or loading limits for various ASME Code service levels, as defined by NF-3113 and NCA-2142.4(b) of Section III, so that these limits can be used in conjunction with the resultant loadings or stresses from the appropriate plant conditions. Because the ASME Code does not specify loading combinations, guidance is needed to provide a consistent basis for the design of component supports. Component supports considered in this guide are located within Seismic Category I structures and, therefore, are assumed to be protected against loadings from natural phenomena (or manmade hazards) other than the specified seismic events. Thus, only the specified seismic events need to be considered in combination with loadings associated with plant conditions to develop appropriate loading combinations. Loadings caused by any natural phenomena other than seismic events should be considered on a case-by-case basis. Regulatory Guide 1.84, “Design, Fabrication, and Materials Code Case Acceptability, ASME Section III,” 2 provides guidance for the acceptability of ASME Code, Section III code cases and their revisions, including ASME Code Cases N-71 and N-249. Code cases identified as