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:
vidual pumps need to be based on data obtained from full-scale experiments performed on pump test stands (e.g., at the pump supplier facility). Tests of sub-scale pumps may be acceptable if full-scale test data are not available, but the conservatism of the scaling rules needs to be demonstrated. b. If the pump excitation frequencies (e.g., rotor speed, VPF and their harmonics) spanning all expected operating conditions of the reactor are within 10 percent of the frequency of a structural or acoustic resonance mode of reactor internals, the vibration analysis needs to assume coincidence between the pump excitation frequency and the resonance frequency. c. The spatial distribution of the combined forcing function from all simultaneously operating pumps depends not only on the number and arrangement of the operating pumps, but also on the phase between the forcing functions of individual pumps. Multiple sources of pump pulsation tones can lead to a “beating” phenomenon, which can magnify the pressure pulsation. At the beating peaks, the pressure pulsations could conceivably be several times those of a single pump. Also, the effects of one or more pumps being out of service on the combined forcing function applied to the reactor internals need to be assessed. Therefore, the vibration analysis of reactor internals needs to address various scenarios of phase difference between the pump forcing functions. For example, if a reactor is operated by 10 pumps, 1 scenario to be analyzed would consider all forcing functions of the 10 pumps to be in phase while another scenario would assume the forcing functions of 5 adjacent pumps to be in phase, but out of phase with those of the other 5 pumps. These two scenarios are not expected to materialize for long periods. However, they would provide indications of the maximum pump loading functions that might occur for short periods of time. d. When computing the system response to RRP excitations, conservative boundary conditions