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:
rest on mounting pads attached to the RPV with variable amounts of contact area and supported load during normal operating conditions, such that there is no simple means for representing the boundary conditions. Another example is that the control rod guide tubes and rods for some SMRs are effectively long beam structures, with structural resonance frequencies depending on the spacing of support structures (the hanger plates). The resonance frequencies vary with rod height. Therefore, evaluation of multiple CRDM/control rod heights is necessary to address all operating and transient conditions of the reactor. If the guide tubes or rods vibrate excessively, they might contact each other during rod movement and interfere with their function. 2.1.2 Forcing Functions The applicant or licensee should determine the design load definition for all reactor internals, including BWR steam dryers, up to the full licensed power level, and validate the methods used to determine the load definitions based on justified SMT or data acquired from other plants. Instrumentation for BWR steam dryers needs to measure pressure loading, strain, and acceleration to confirm the SMT, plant data, and analysis results. For EPU requests, BWR plant data at current licensed power conditions should be used to confirm the results of the SMT and analysis for the steam dryer load definition. DG-1323, Page 15 The applicant or licensee should describe the estimated random and deterministic forcing functions, including very low-frequency components, for steady-state and anticipated transient operation for reactor internals that might be adversely affected by FIV, AR, AIV and MIV. Acceptable methods are summarized below. Applicants for new designs, particularly SMRS, should consider additional relevant forcing functions which are not described here. The applicant or licensee should determine the excitation mechanisms that are relevant to the various structural components and evaluate the forcing