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:
PWR nuclear power plants, the internal components of steam generators also must be included in the dynamic analysis. The purpose of this analysis is to assess the vibration behavior of the components, including the definition of the input-forcing functions and estimation of the consequent vibration and stress levels. Before conducting the analyses, applicants/licensees should address the specific locations for calculated responses, the considerations for selecting the mathematical models and computer software, the interpretation of analytical and numerical results and concomitant bias errors and uncertainties, the acceptance criteria, and the methods for verifying predictions by means of tests. 3.9.2-5 Revision 3 - March 2007 The analyses should consider such various flow excitation mechanisms 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. 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 and/or structural resonances, causing high dynamic loads throughout the steam system and RPV. These “self-excited” loads are 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 which lead to adverse flow effects at all expected reactor operating conditions should be conducted by the applicant/licensee. The following areas related to the dynamic response analysis are reviewed along with their bias errors and uncertainties. A. Results of vibration and stress calculations. The calculated vibration and stress levels in reactor internal structures and in main steam line (MSL) valves are reviewed with their safety margins. The results