Document: NRC Regulatory Guide
Document ID: 111e064c-2d28-4647-872a-806b29019408
Document Type: regulatory_guide
Title: Design Limit and Loading Combinations for Seismic Category I Fluid System Components
Source: NRC Regulatory Guide Division 1
Source URL: https://www.nrc.gov/docs/ML1229/ML12298A124.pdf
Revision Date: 2023-06
Chapter: 
Section ID: RG-1.48
CFR Part: 
CFR Title: 

Content:
3) is required. However, neither Section III nor any other published national code or standard provides adequate guidance for selecting code classifications and loading combinations for design or for identifying Seismic Category I fluid system components. The lack of adequate guidance: for selecting loading combinations is apparent from. a review of recent construction permit applications which :reflect design requirements, as contained in the code design specifications. For e~sentially identical components designed for the same plant conditions (i.e., operating conditions of the plant categorized as normal, upset, emergency, and faulted plant conditions) and specified seismic events (i.e., one-half the Safe Shutdown Earthquake (SSE) and the SSE) the. loading combinations and asso'ciated design limits, vary considerably : among applications for construction permits. Regulatory Guides 1.26 and 1.29 (Safety Guide 26 and 29) entitled "Quality Group Classifications and Standards" and "Seismic Design Classification," respectively, provide acceptable bases for classifying fluid system components in relation to applicable national codes (e.g., Section III of the ASME Code) and for-identifying th6se striuctures, systems and components that: should be designed to remain functional under the effects Of the SSE (i.e., Seismic Category I structures, systems, and components). To further provide a consistent basis for design of fluid system comipoiient's important to safety, this guide delineates acceptable design limits and appropriate combinations' of, loadings associated with applicable plant conditions arid specified seismic events. The approach set' forth in this guide is directly related to Section III of the ASME Code. Design limits as specified in Section III are extensively utilized to provide assurance of ýthie pressure-retaining integrity of vessels, piping, non:active pumps, and non-active valves of each Code class; however',: for the particular case of active