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:
ssure measurement details are provided in Section C.2.2 of this regulatory guide): a. At least two measurement locations need to be used on each MSL. However, using three measurement locations on each MSL improves input data to acoustic propagation models, particularly if the locations are spaced logarithmically. This configuration will reduce the uncertainty in describing the waves exiting and entering the RPV. Acoustic sources should not exist between any of the measurement locations, unless specifically justified. b. Acoustic modeling parameters, such as the speed of sound, reflection coefficients from boundaries between steam and water, and sound attenuation (damping), may be adjusted when developing and benchmarking models against measurements, but should not deviate significantly from those based on theory and measurement. c. All acoustic wavelengths over all frequencies with significant loading need to be resolved by discretizing with at least six subdivisions. d. Circular regions of acoustic models, such as MSL inlets in RPVs, need to be represented in a manner that properly encompasses the actual area of the circular cross section. Linearly subdividing a circular region in a numerical model can artificially reduce the effective cross sectional area. Once specified and benchmarked, the same speed of sound, attenuation coefficient, and reflection coefficient may be used in similar plants. However, different flow conditions (temperature, pressure, quality factor) might dictate adjustments of these parameters within reasonable expectations. Mechanical and Acoustic Forces from RRPs Where applicable, the vibration analysis needs to examine the effects of RRPs by pulsation on reactor internals. Analysis of AIV and MIV involves knowledge of the RRP forcing functions. Operating RRPs generate various exciting forces at multiples of their drive frequency, including those induced by electromagnetic oscillations within motor cores, by imbalance and misalignment (which