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:
primary bending stresses~and are derived on a basis that is comparable to the design limits for Code Class I components designed by analysis. One hundred ten percent of S and 120 percent of S (and the limilts for primary membrane plus primary bending) are analogous to the design limits for the upset operating condition category and the emergency operating condition category, respectively, given in NB-3200 of Section 11I. Therefore, to assure pressure-retaining integrity, the primary membrane stress should not be exceeded by more than 10 percent of S, and the sumn of the primary membrane plus primary bending stresses should not be exceeded by more than 65 percent of S for the combination of loadings delineated in regutlatory positions 9.a.(]), and '9.a.(2). The primary membrane stress and thfe surn of the primary membrane plus primary bending stresses should not be exceeded by nlore than 20 percent and 80 percent of S. respectivel'. for the combination of loadings delilneated in regulatory position 9.b. Active ASME Code Class 2 and 3 Pumps For active Code Class 2 and 3 pumps the primary llemllbrane stress should not exceed S. and tile surn of the primary membrane plus primary bending stresses should not be exceeded by more than 50 percent of S fbr the combination of loadings delineated in regulatory positions 10.a.( I ), 10.a.(2), and 10.a.(3). These limits are analogous to tile normal operating condition category design limits of NB-3200 of Section Ill of the ASME Code and thus provide increased assurance that unacceptable deformations affecting operability of active Code Class 2 and 3 pumps will not result. In addition to compliance with the design limits specified. demonstration- of operability as outlined by Note I1 to tl1e reCulatory position should also be provided. Note II is identical to Note 6 to the regulatory position except that the design limits for non0-active pumps and valves may be used for the applicable loading combinations if appropriate analyses