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:
itivity analyses of the effect of the sample length of the pressure signal on the PSDs need to be performed to ensure bounding estimate of the loading functions. g. When evaluating the growth rates of resonance peaks as a function of power level, the root mean square (RMS) amplitude within a relatively narrow frequency band centered around the resonance peak needs to be evaluated and not the total RMS amplitude of the entire frequency range. The boundaries of the resonant frequency band can be placed at the interface between the resonance peak and the neighboring background representing the broadband response. h. When conducting SMTs, particularly under transient test conditions, the uncertainties associated with determining the flow velocity (or Mach number) during the tests need to be analyzed. SMTs need to be performed up to slightly higher power levels than the maximum expected power in the full scale installation to compensate for the uncertainties in determining the flow velocity during the SMT. i. For self-excited vibration and acoustic resonance mechanisms with lock-in phenomena, the absolute value of flow excitation level (e.g., forcing function or amplitudes of vibration and pressure pulsation) measured from the SMT cannot be scaled up to full- scale plant conditions. This is because the measured variable in the SMT is influenced by the associated system response, which is different from the plant response. However, ratios of excitation levels measured from the SMT, if performed adequately, can be used to scale in-plant measured excitation levels to higher power levels. In previous EPU applications, this ratio is referred to as a “bump-up-factor” (BUF). Using BUFs obtained from SMTs should be compared to BUFs determined from in-plant measurements from prototype plants to demonstrate that the results are bounding. BUFs represent the ratios between the dynamic loadings at a power level to that measured at a lower power level. In addition, BUFs are