Document: NRC Regulatory Guide
Document ID: ad61f8a3-1cce-4446-9542-dcdda55c1ec6
Document Type: regulatory_guide
Title: Comprehensive Vibration Assessment Program for Reactor Internals During Preoperational and Initial Startup Testing + HISTORY - HISTORY 07/2015 – DG-1323 , Proposed Revision 4 03/2013 – Periodic Review of Revision 3 – No Issues Identified 11/2006 – DG-1163 , Proposed Revision 3 (Rev. 4)
Source: NRC Regulatory Guide Division 1
Source URL: https://www.nrc.gov/docs/ML1508/ML15083A390.pdf
Revision Date: 2023-06
Chapter: 
Section ID: RG-1.20
CFR Part: 
CFR Title: 

Content:
stress at locations susceptible to fatigue cracking with the ASME BPV Code fatigue limits to validate the end-to-end analysis. If necessary, the applicant/licensee should perform modifications to the structure or other components to DG-1323, Page 13 demonstrate design margin to Code allowable limits. The BWR applicant or licensee should perform a rigorous assessment of stress in steam dryers. 2.1.1 Structural, Hydraulic, and Acoustic Modeling The vibration and stress analysis program in the CVAP should address the following aspects related to structural, hydraulic, and acoustic modeling: a. the structural models used to compute the vibration response of reactor internals. b. other models of steam or water volumes coupled to the structure. c. natural frequencies and associated mode shapes that might be excited during steady-state and anticipated transient operation for reactor internals. d. frequency response functions (FRFs) between key drive and response locations, along with the assumed damping used in the calculations, expressed as vibration or stress normalized by input force. Acceptable methods are summarized below. Modes of Vibration The applicant or licensee should develop tables of significant structural natural frequencies and accompanying figures of corresponding mode shapes. Benchmarking the analytic mode shapes and natural frequencies involves comparison of measured and simulated data. The differences between measured and simulated natural frequencies are used to establish uncertainty ranges for FRFs and final response calculations. If benchmarking reveals that the simulated natural frequencies are within +/-10 percent of those measured, FRFs and final responses are computed over that range of uncertainty. The forcing function time histories are expanded and compressed by +/-10 percent and applied repeatedly to the structural dynamic model, with the worst case values retained and applied in the analysis. Several analysis increments are used, depending