Document: NRC Regulatory Guide
Document ID: c55ba6c5-aa2d-4ad6-aba2-2001e16524ab
Document Type: regulatory_guide
Title: Ultrasonic Testing of Reactor Vessel Welds During Preservice and Inservice Examinations (Rev. 1)
Source: NRC Regulatory Guide Division 1
Source URL: https://www.nrc.gov/docs/ML1221/ML12216A015.pdf
Revision Date: 2023-06
Chapter: 
Section ID: RG-1.150
CFR Part: 
CFR Title: 

Content:
. 2. CALIBRATION I System calibration should be checked to verify the DAC curve and the sweep range calibration per nonmandatory Appendix B, Article 4, Section V of the ASME Code, as a minimum, before and after each RPV examination (or each week in which it is in use, whichever is less) or each time any component (e.g., transducer, cable, connector, pulser, or receiver) in the examination system is changed. Where possible, the same calibration block should be used for successive in- service examinations of the same RPV. The calibration side holes in the basic calibration block and the block surface should be protected so that their characteristics do not change during storage. These side holes or the block surface should not be modified in any way (e.g., by polishing) between successive examinations. If the block surface or the calibration reflector holes have been polished by any chemical or mechanical means, this fact should be recorded. 2.1 Calibration for Manual Scanning For manual scanning for the sizing of flaws, static calibra- tion may be used if sizing is performed using a static trans- ducer. When signals are maximized during calibration, they should also be maximized during sizing. For manual scanning for the detection of flaws, reference hole detection should be A shown at scanning speed and detection level set accordingly (from the dynamic DAC). 1.150-6 2.2 Calibration for Mechanized Scanning When flaw detection and sizing are to be done by mechanized equipment, the calibration should be performed using the following guidelines: a. Calibration speed should be at or higher than the scanning speed. b. The direction of transducer movement during calibra- tion should be the same as the direction during scanning unless (1) it can be shown that the change in scanning direction does not make a difference in the sensitivity and vibration background noise received from the search unit or (2) these differences are taken into account by a correction factor. c. For