Document: NRC Regulatory Guide
Document ID: a03860d0-46a2-4c53-b0e5-9398a146bf12
Document Type: regulatory_guide
Title: Safety-Related Steel Structures and Steel-Plate Composite
Source: NRC Regulatory Guide Division 1
Source URL: https://www.nrc.gov/docs/ML2033/ML20339A558.pdf
Revision Date: 2023-05
Chapter: 
Section ID: RG-1.243
CFR Part: 
CFR Title: 

Content:
B2-9). 2.1.3. Loads resulting from pool dynamics for SC structures in pressure-suppression containments should be analyzed. Licensees and applicants should justify the methods of analysis used. 2.1.4. The design for loads due to accidental explosions, accidental vehicle impacts, or small aircraft impacts should use load combination (NB2-7) with those loads in lieu of Wt, as well as further guidance provided in Appendix N9 to ANSI/AISC N690-18. The Wt load in the load combination (NB2-7) should be evaluated for both tornado and hurricane loads applicable to the site for which related regulatory guidance is covered in RG 1.76 and RG 1.221, respectively. RG 1.217 cover the effects from beyond-design-basis large aircraft impacts, which are outside the scope of this RG. 2.1.5. In load combination (NB2-9), 0.7Ess is to be combined absolutely with the accident loads. In lieu of this, 1.0Es may be combined with the accident loads by the Square-Root- of-the-Sum-of-the-Squares (SRSS), if all the provisions of ANSI/AISC N690-18, Commentary Section NB2.5, Paragraph 4, are satisfied. 2.2. ANSI/AISC N690-18, Section NB2.6, Allowable Strength Design Unless otherwise justified, the NRC staff endorses the allowable strength design (ASD) load combinations in Section NB2 as modified in Table 2 (modifications indicated in bold font). Table 2 Load Combinations for the ASD Method ASD Required Strength (U) Load Combinations N690 Equation U = (D + F) + (Ro + To) + C NL (NB2-10) U = (D + F) + (L + H + Ro + To) + C + 0.75(Lr or S or R) NL (NB2-11) U = (D + F) + (0.75L + 0.75H + 0.75Ro + To) + C + 1.0(Lr or S or R) NL (NB2-12) U = (D + F) + (1.0L + 1.0H + Ro + To) + 0.6W + C + 0.75(Lr or S or R) SEL (NB2-13) U = (D + F) + (1.0L + 1.0H + Ro + To) + Eo + C + 0.75(Lr or S or R) SEL (NB2-14) U = D + F + L + H + To + Ro + Es + C EEL (NB2-15) U = D + F + L + H + To + Ro + Wt EEL (NB2-16) U = D + F + L + H + Ta + Ra + Pa + C AL (NB2-17) U = D + F + L + H + Ta + Ra + Pa + Yr + Yj + Ym + 0.7Es AL