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:
back metal surface roughness should be related to the volume of material near each surface that is not being examined. 4. BEAM PROFILE The beam profile should be determined if any recordable flaws are detected. This should be done for each search unit used during the examination by a procedure similar to that outlined in the nonmandatory Appendix B (B-60), Article 4, Section V of the ASME Code, 1980 edition, for determining beam spread. Beam profile curves should be determined for each of the holes in the basic calibration block. Interpola- tion may be used to obtain beam profile correction for assess- ing flaws at intermediate depths for which the beam profile has not been determined. 5. SCANNING WELD-METAL INTERFACE The beam angles used to scan welds should be based on the geometry of the weld/parent-metal interface. At least one of these angles should be such that the beam is almost perpendicular (±15 degrees to the perpendicular) to the weld/parent-metal interface unless it can be demonstrated that unfavorably oriented planar flaws can be detected by 1.150-7 the UT technique being used. Otherwise, use of alternative volumetric NDE techniques, as permitted by the ASME Code, should be considered. Alternative NDE techniques may be considered to include high-intensity radiography or tandem-probe ultrasonic examination of the weld-metal interface. 6. SIZING Indications from geometric sources need not be recorded. 6.1 Traveling Indications Indications that travel on the horizontal baseline of the scope for a distance greater than indications from the calibration holes (at 20 percent DAC amplitude) should be recorded. Indications that travel should be recorded and sized at 20 percent DAC. Where the indication is sized at 20 percent DAC, this size may be corrected by subtracting for the beam width in the through-thickness direction obtained from the calibration hole (between 20 percent DAC points) that is at a depth similar to the flaw depth. If the indication exceeds