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:
rtainties in the Strouhal number), (2) effects of the ratio between the standpipe and main pipe diameters, (3) effects of edge radii at the inlet of the standpipes, (4) effects of upstream elbows, (5) distance between standpipes, and (6) relative length of standpipes. b. Shear layer excitation of “trapped acoustic modes” associated with shallow cavities in isolation gate valves attached to MSLs in BWRs. Several methods may be used to quantify forcing functions, including SMT, CFD, and Acoustic Inference Methods. Guidance for these methods is provided below: Scale Model Testing If SMT is used to support the analysis, the following aspects need to be addressed: a. SMT facilities generally involve a lower Reynolds number than that present in actual nuclear power plants because of the smaller scale and lower static pressure of the SMT. Because self-excitation mechanisms (such as flow-excited acoustic resonance) are generally dependent on Reynolds number, the applicant or licensee should demonstrate that the SMT results are not influenced by further increases in the Reynolds number of the SMT. b. When examining flow-excited acoustic resonance mechanisms, the differences between the model parameters and those of the full scale installation need to be evaluated. These include, but are not limited to, acoustic attenuation of sound waves and reflection coefficient at the model boundaries. Acoustic attenuation is affected by component size (e.g., pipe diameter), static pressure, and void fraction of the medium (e.g., the wetness degree of steam or air). Scale models built to study acoustic resonance excitation are generally designed with reflective boundary conditions to enhance the quality factor of the resonant modes and, thereby, obtain conservative data. c. SMT to examine fluid-structure interaction mechanisms needs to be conducted on dynamically similar scale models based on all relevant dimensionless parameters of the full-scale installation. Scale models based on