Document: NRC Regulatory Guide
Document ID: b6726dc6-2968-4ca9-a925-c831eaaecc69
Document Type: regulatory_guide
Title: 03/2007
Source: NRC Regulatory Guide Division 1
Source URL: https://www.nrc.gov/docs/ML0702/ML070260029.pdf
Revision Date: 2023-06
Chapter: 
Section ID: RG-1.61
CFR Part: 
CFR Title: 

Content:
eismic Design Criteria for Structures, Systems, and Components in Nuclear Facilities” [Ref. 13], and Non-Mandatory Appendix N, “Dynamic Analysis Methods,” to Section III, Division 1, of the ASME Boiler & Pressure Vessels Code [Ref. 14]. In addition, NUREG/CR-6919 [Ref. 12] provides recommendations and commentary on damping values for (1) containment structures, containment internal structures, and other Seismic Category I structures; (2) piping; (3) electrical distribution systems (i.e., cable tray or conduit systems); (4) HVAC; and (5) mechanical and electrical components. Regulatory Position 5 in Section C of this revised guide provides the damping values that resulted from the staff’s review of this industry guidance. Rev. 1 of RG 1.61, Page 4 C. REGULATORY POSITION The following regulatory positions provide acceptable damping values to be used in the elastic dynamic seismic analysis and design of SSCs, where energy dissipation is approximated by viscous damping unless otherwise specified. Damping values higher than those provided may be used if documented test data support the higher values. Damping values associated with soil-structure interaction analysis are not within the scope of this regulatory guide. 1. Structural Damping 1.1 Acceptable Structural Damping Values for Containment Structures, Containment Internal Structures, and Other Seismic Category I Structures 1.1.1 Safe-Shutdown Earthquake (SSE) Table 1 provides acceptable damping values for the SSE analysis. Table 1. SSE Damping Values Structural Material Damping (% of Critical Damping) Reinforced Concrete 7% Reinforced Masonry 7% Prestressed Concrete 5% Welded Steel or Bolted Steel with Friction Connections 4% Bolted Steel with Bearing Connections 7% Note: For steel structures with a combination of different connection types, use the lowest specified damping value, or as an alternative, use a “weighted average” damping value based on the number of each type present in the structure. 1.1.2