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:
natural frequencies and shapes of the dominant modes, should be characterized. In analyses of a component structural element basis, the presence of dynamic coupling among component structure elements should be investigated. Upper bounds on the uncertainties of all natural frequencies of the relevant resonance modes should be provided. The uncertainties and bias errors of the amplitudes of the frequency response functions (FRFs) also should be provided. The uncertainties and bias errors may be estimated from comparisons of simulations to measurements made on structures similar in construction to the reactor internal being modeled. The performance of hammer tests would be expected for replacement steam dryers. (iv) Dynamic responses of reactor internals to self-excited flow oscillations should be estimated. The applicants/licensees should analyze in detail adverse flow effects generated by various excitation mechanisms like vortex-induced vibration flow-excited acoustic resonance, fluid-elastic 3.9.2-16 Revision 3 - March 2007 instability, and other flow instabilities (e.g., separated and impinging flow instabilities). These mechanisms may be assessed by theoretical, numerical, or experimental techniques, including scale model testing. The analysis should clearly identify whether each mechanism will be excited during the planned operating range of the power plant. Full dynamic analysis is requested for mechanisms expected to generate adverse flow effects, including estimation of vibration and stress amplitudes at the critical locations and, in particular, where vibration sensors will be mounted on the reactor internals. RG 1.20, Section C.2.1.3 provides more guidance on self-excited flow instabilities. (v) The dependance of the dynamic response on hydrodynamic excitation forces like coolant recirculation pump frequencies and the flow path configuration should be evaluated. Any frequency coincidence between the pump blade passing frequency and the natural frequencies