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:
y positions 3.a., 3.b., and 3.c., respectively. One hundred ten percent and 120 percent ,of Pr, respectively, are analogous to the upset and emergency operating condition category limits of NB-3200 of Section III. One hundred fifty percent of Pr is analogous to the hydrostatic test pressure specified for Code Class 1 valves in Section III. Active ASME Code Class 1 Pumps and Valves (Designed by Analysis) The normal operating condition category design limits given by NB-3222 of Section III should be applied to design active pumps and valves for the combination of loadings delineated in regulatory positions 4.a.(l), 4.a.(2), and 4.a.(3). The design limits of NB-3222 are selected because the primary stress intensities associated with those limits are in the elastic range and thus provide greater assurance of operability for pumps and valves (i.e., less probability of unacceptable deformations that would impede or prevent operation) than the design limits for the upset, emergency, and faulted operating condition categories of Section Ii. Secondary effects (stresses and deformations,) in components whosc •"" function is pressure retention are not usually evaluated for the loading combinations delineated in regulatory positions '4.a.( 2) and 4.a.(3). However, these effects should be considered for active Class I pumps and valves so that unacceptable' deformations do not result. Local effects (peak stresses) 'need not be evaluated for these loading combinations. In addition to compliance with the design limits specified, demonstration of operability as outlined by Note 6 to the regulatory position should also be provided. Note 6 suggests appropriate testing, analysis, or combinations of those measures that should be implemented to demonstrate the operability of active pumps and valves under all design loadinig'combinations. However, Note 6 states that the design limits for non-active pumps and valves designed by analysis may be used if assurance is provided by detailed