Document: NUREG-0800
Document ID: 7c104096-d040-463a-a94b-a0af08ab3478
Document Type: srp
Title: DYNAMIC TESTING AND ANALYSIS OF SYSTEMS, STRUCTURES, AND
Source: NUREG-0800
Source URL: https://www.nrc.gov/docs/ML0702/ML070230008.pdf
Revision Date: 2023-06
Chapter: 3
Section ID: 3.9.2
CFR Part: 
CFR Title: 

Content:
y measurements in nuclear power plants. (2) CFD: If CFD simulations are used to develop unsteady forcing functions, the following areas should be considered. (a) Include acoustic/vibration coupling to simulate enhancement of flow instabilities (if any). (b) Grid size sensitivity tests. (c) The Courant number requirement should be met. (d) There should be unsteady simulations using Large Eddy Simulation (LES) or Direct Numerical Simulation (DNS) at high Reynolds number flow and including compressibility effects to model any coupling of the flow with the acoustic waves in the fluid (self-excitation or lock-in effects). 3.9.2-18 Revision 3 - March 2007 (e) Real gas simulation should be used (i.e., use state equation of steam as real gas). (f) The simulation procedures should be validated on similar (i.e., complex and high Reynolds number) flow situations. (3) Acoustic Modeling of Steam System: If an acoustic model of the steam system (the steam within the MSLs and the RPV) computes fluctuating pressures within the RPV and on BWR steam dryers inferred from measurements of fluctuating pressures within the MSLs connected to the RPV, the following areas should be considered. (a) There should be at least two measurement locations on each MSL in a BWR; however, three measurement locations on the MSLs improve input data to an acoustic model, particularly if the locations are spaced logarithmically, reducing uncertainty in describing the waves coming from and going into the RPV. With two or three measurement locations, there should be no acoustic sources between the measurement locations, unless justified. (b) Strain gages (at least four gages circumferentially oriented and placed at equal distance along the circumference) may be used to relate the hoop strain in the MSL to the internal pressure. Strain gages should be calibrated according to the MSL dimensions (diameter, thickness, and static pressure). Alternatively, pressure measurements made with transducers flush-mounted