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:
ding the bias errors and uncertainties from the end-to-end vibration and stress analyses, need to also include errors and uncertainties associated with the vibration and stress measurement program (in particular, those associated with the data acquisition systems and instrumentation). The MSLs may be instrumented to collect data to estimate steam pressure fluctuations and to identify the presence of flow-excited acoustic resonances that might adversely affect MSL valves and steam dryers. The direct steam dryer measured data need to be used to calibrate the MSL instrumentation and data analysis for dryer forcing function estimation before removal or failure of an excessive number of the steam dryer sensors that precludes a reliable analysis. EPU experience has shown that the application of MSL pressure measurements is complex. Strain gage arrays may be used to relate the hoop strain in an MSL to the internal pressure. However, although accurate individual strain measurements on a flat surface are straightforward, measuring a summed set of signals across a circumferentially oriented array of strain gages in a highly pressurized pipe with curved surfaces is more challenging. The net hoop strain is often a small fraction of the total strain at a given sensor location, and the total strain can include significant bending and ovaling of components. System errors or background noise in the array installation can therefore have much larger effects on a summed array measurement than on a single sensor measurement. Sensor and weld integrity, non-uniform circumferential wall thickness distributions, wiring, and data acquisition issues (such as erroneous gain and/or calibration factors) have caused difficulties in past applications. Measurement guidance is provided below: DG-1323, Page 29 a. One means to help verify in-situ calibration of a strain gage array to pressure is to perform a static pressurization calibration where measured hoop strain is compared directly to plant