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:
% 5% Welded 4% 3% Rev. 1 of RG 1.61, Page 9 5. Mechanical and Electrical Component Damping Table 6 presents the damping values for mechanical and electrical components, which are applicable to passive subcomponents that can be seismically qualified by analysis. Active subcomponents do not readily lend themselves to seismic qualification by analysis, and require qualification by test, as described in Section 3.10 of NUREG-0800 [Ref. 15]. Table 6. Damping Values for Mechanical and Electrical Components Component Type Damping Value SSE OBE > SSE/3 Motor, Fan, and Compressor Housings (protection, structural support) 3% 2% Pressure Vessels, Heat Exchangers, and Pump and Valve Bodies (pressure boundary) 3% 2% Welded Instrument Racks (structural support) 3% 2% Electrical Cabinets, Panels, and Motor Control Centers (MCCs) (protection, structural support) 3% 2% Metal Atmospheric Storage Tanks (containment, protection) — Impulsive Mode — Sloshing Mode 3% 0.5% 2% 0.5% Rev. 1 of RG 1.61, Page 10 D. IMPLEMENTATION The purpose of this section is to provide information to applicants and licensees regarding the NRC staff’s plans for using this regulatory guide. No backfitting is intended or approved in connection with the issuance of this guide. Except in those cases in which an applicant or licensee proposes or has previously established an acceptable alternative method for complying with specified portions of the NRC’s regulations, the NRC staff will use the methods described in this guide to evaluate (1) submittals in connection with applications for construction permits, standard plant design certifications, operating licenses, early site permits, and combined licenses; and (2) submittals from operating reactor licensees who voluntarily propose to initiate system modifications if there is a clear nexus between the proposed modifications and the subject for which guidance is provided herein. REGULATORY ANALYSIS / BACKFIT ANALYSIS The regulatory analysis and backfit