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:
ccordance with Section VIII, Division 2, of the ASME Code) and do not yet provide any design rules for pumps. Furthermore, no design limits for other than the normal plant condition are available (the one exception to this is piping). Generally, Class 2 and 3 components are of somewhat lower quality as related t0' material, fabrication, and. nondestructive examination requirements than Code Class I components. Because of less stringent design requirements and a lower quality level in comparison to Code Class 1 components; the design limits selected for Code Class 2 and 3 non-active components are, on a comparable basis, lower for the combination of loadings associated With the emergency and faulted plant conditions than for Code Class 1 non-active components. The same considerations that apply to Code Class I active pumps and valves apply to Code Class 2 and 3 active pumps and valves. ASME Code Class 2 and 3 Vessels (Designed to Division 1 of Section VIii) To provide assurance of pressure-retaining integrity for Code Class 2 and 3 vessels, the allowable stress value S should not be exceeded by more than 10 percent for the combination of loadings delineated' in 'regulatory positions 6.a.(1), and 6.a.(2), and S should not be exceeded by more than 50 percent-for the combination 1.48-3, of loadings specified by regulatory position 6.b. One hundred ten percent of S is analogous to the upset operating condition category design limitsspecified for Code Class I components, while 150 percent of S is comparable to the membrane stress that would occur in a cylindrical or spherical shell during hydrostatic testing. Both limits are within the elastic stress range for ferritic materials. If a more detailed analysis is performed. noloe 9 to the regulatory position provides limits for prinoary membrane and primary bending stresses. ASME Code Class 2 Vessels (Designed to Division 2 of Section VIII) Section III of the ASME Code allows Code Class 2 vessels to be designed in accordance