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:
s to evaluate potential adverse effects. For SMRs, components such as CRDMs and steam generators (SGs) might be within or directly connected to the reactor pressure vessel (RPV). Consolidating reactor and reactor coolant system components into a single integral reactor module creates the potential for increased FIV and MIV. For FIV, these include primary coolant flow over the control rod tubes and drive mechanisms; flow through RRPs; flow through and around the SG tube assemblies; flow through valves; and turbulent steam flow passing over valve standpipes attached to the MSLs. For MIV, the RRPs and the valves could also generate mechanical excitation tones in connected piping and other structures. If exciting frequencies coincide with the natural frequencies of the SSCs or acoustic resonance frequencies, unacceptable vibration levels could occur. Excessive vibration could lead to (a) fatigue failure of various reactor internals, (b) loose parts causing erosion or wear in reactor internal parts, and (c) interference with the operation of the CRDS. This guide discusses methods to assess the vibratory loading on reactor internals induced by various sources, including those from pumps and valves. However, the vibration of pumps, valves, and any other non-internal components is not within the scope of this regulatory guide. A reliable evaluation of potential adverse effects of FIV, AR, AIV and MIV on nuclear power plant components includes the proper consideration of bias errors and uncertainties in the predictive analysis and in the measurement program. Bias errors might result from the under-prediction of pressure loading, stress, strain, or acceleration when modeling SSCs and acoustic volumes. They might also result from errors in the measurement of data used to benchmark prediction methods. Uncertainties might result from the random error associated with measurement of plant parameters. Guidance is provided herein for assessing end-to-end bias and uncertainty to