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:
gle Beam Profile Characterization The vertical beam profile should be determined for each search unit used during the examination by a procedure similar to that outlined in nonmandatory Appendix B-60, Article 4, Section V of the ASME Code or Appendix I to Section XI of the ASME Code. Beam profile curves should be determined at different depths to cover the thicknesses of materials to be examined. Interpolation may be used to obtain beam profile correction for assessing flaws at intermediate depths for which beam profile has not been determined. Beam profile measurements should be made at the sensitivity required for sizing. For example, sizing to a 20 percent DAC criteria requires that the beam profile be determined at 20 percent DAC. 2. CALIBRATION System calibration should be performed to establish the DAC curve and the sweep range cali- bration in accordance with Article 4, Section V of the ASME Code or Appendix I to Section XI. Calibration should be confirmed before and after each RPV examination, or each week in which the system is in use, whichever is less. Where possible, the same calibration block should be used for successive inservice examinations of the RPV. 2.1 Calibration for Manual Scanning For manual sizing of flaws, static calibration may be used if sizing is performed using a static transducer. 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 shown at scanning speed and detection level set accordingly. 1.150-11 2.2 Calibration for Mechanized Scanning When flaw detection is to be done by mechanized equipment, the calibration should be performed using the following guidelines. a. The DAC curve should be established using either a moving transducer mounted on the mechanism that will be used for examination of the component or a mechanism that duplicates the critical factors (e.g., transducer mounting, weight, pivot points,