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:
3, 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 pressure. b. Four strain gages, evenly spaced around a pipe circumference, are necessary to filter non- breathing signals from a measurement. Based on experience, additional gages are needed to provide redundancy because of the frequent failure of gages under plant operating conditions. c. If MSL measurements are repeated in the future with replaced gages, these measurements need to be compared with previous data to ensure reasonable consistency. d. Instrumentation wiring needs to be properly labeled. MSL strain gage spectra need to be compared for similar locations to ensure reasonable consistency and that mislabeling has not inadvertently occurred. e. MSL strain measurements acquired at different times, such as during the application process and during power ascension, might differ because of aging of the gages, gage welding, wiring, and data acquisition. In some cases, individual sensors might fail leading to changes in the summed array signal used to infer pressures. In these cases, comparisons to previous MSL data and any derived limits need to be made with consistent sensor sets. For example, any sensors in an MSL circumferential array that fail need to be removed from the array summation in both new and previous datasets, as well as limits and limit curves. 2.2.2 In-plant Measurement Issues In-plant measurements of surface pressures, vibration (via accelerometers), and strain (via strain gages) can be affected by several mechanisms. Guidance for the in-plant measurement program is provided below: a. All in-plant instrumentation needs to be qualified for the environment in which it will operate. b. Bench testing of sensors in representative environments and on structures similar to those in the plant is necessary to establish guidelines for installation and data