Document: NRC Regulatory Guide
Document ID: 1d715751-9321-4481-a46f-4ff802a5efe0
Document Type: regulatory_guide
Title: Service Limits and Loading Combinations for Class 1 Linear-Type Supports + HISTORY – HISTORY 10/2006 – DG-1168 , Proposed Revision 2
Source: NRC Regulatory Guide Division 1
Source URL: https://www.nrc.gov/docs/ML0630/ML063000449.pdf
Revision Date: 2023-06
Chapter: 
Section ID: RG-1.124
CFR Part: 
CFR Title: 

Content:
ised even when using the plastic analysis method in the methodology combination approved in Appendix F. This is especially important for identifying buckling or instability problems when the change of geometry should be considered to avoid erroneous results. Function of Supported System In selecting the level of service limits for different loading combinations, the decision should take into account the function of the supported system. To ensure that systems will operate properly regardless of plant condition if their normal function is to prevent or mitigate the consequences of events associated with an emergency or faulted plant condition [e.g., the function of the emergency core cooling system (ECCS) during faulted plant conditions], use of the Level A or B service limits specified in Subsection NF of the ASME Code Section III (or other justifiable limits provided by the Code) is appropriate. Because NF-3320 derived all equations from American Institute of Steel Construction (AISC) rules and many AISC compression equations have built-in constants based on mechanical properties of steel at room temperature, it would be imprudent to use these equations indiscriminately for all NF sections and the latest accepted version of ASME Code Cases N-71 and N-249 involving materials at all temperatures. For materials other than steel and/or for working temperatures substantially different from room temperature, these equations need to be rederived with the appropriate material properties. DG-1168, Page 5 Deformation Limits Because component supports are deformation-sensitive load-bearing elements, satisfying the service limits of Section III will not automatically ensure their proper function. If specified by the Code design specification, deformation limits might be the controlling criterion. However, if a particular plant condition does not require the function of a component support, the stresses or loads resulting from the loading combinations under that plant condition