Document: NUREG-0800
Document ID: 6b7eddf4-f7ce-4821-9f11-e37070221e57
Document Type: srp
Title: DYNAMIC TESTING AND ANALYSIS OF SYSTEMS, STRUCTURES, AND
Source: NUREG-0800
Source URL: https://www.nrc.gov/docs/ML1613/ML16133A418.pdf
Revision Date: 2023-06
Chapter: 3
Section ID: 3.9.2
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CFR Title: 

Content:
uide tubes · Feedwater lines Note that new reactor internals designs might include additional components not in the lists above that need to be evaluated. The purpose of the analyses is to assess the vibration behavior of the components, including the definition of the input-forcing functions, and estimation of the consequent vibration and alternating stress levels. The analyses should verify the structural integrity of reactor internals for flow-induced vibration (FIV), acoustic resonance (AR), acoustic-induced vibration (AIV), and mechanical-induced vibration (MIV). Flow excitation mechanisms such as vortex-induced vibration, flow-excited acoustic resonance, fluid-elastic instability, and turbulence buffeting as well as other flow excitations of flow separation, reattachment, and impinging flow instabilities should be considered. These mechanisms are often nonlinear and their adverse effects cannot be predicted by linear extrapolation of existing plant data. In some cases, the instabilities in these flow fields can couple with acoustic or structural resonances, causing high dynamic loads throughout the steam system and RPV. These self-excited loads can be orders of magnitude higher than those which do not couple to acoustic or structural resonances. A complete assessment of the likelihood of any potential self-excitation mechanisms that lead to adverse flow effects at steady state and anticipated transient conditions that correspond to preoperational, startup test, and 3.9.2-6 Revision 4 – March 2017 normal operating conditions is needed. AIV and MIV due to pressure pulsation and vibration of the reactor recirculation pump (RRP) should also be reviewed for all SSCs, including reactor internals. The following areas related to the dynamic response analysis are reviewed along with their bias errors and uncertainties. For more details on NRC guidance to applicants, refer to RG 1.20, Revision 4, Section C.2. A. Structural, Hydraulic, and Acoustic Modeling. All