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:
he start and stop control points should include the entire required thickness including the material near each surface. If a single gate is used, it should be capable of recording multiple indications appearing in the gate. Alternative means of recording may be used provided they do not reduce flaw detection and recording capability. Examination should be done with a minimum 25 percent scan overlap based on the transducer element size. The capability to effectively detect defects at the internal clad/base metal interface shall be considered acceptable if the exami- nation procedure(s) or technique(s) meet the requirements of Section 6.0 of this document and demonstrate the following: a. Procedures for examination from the outer surface, or when using full vee from the inside surface, should include the use of the 2 percent notch which penetrates the internal (clad) surface of the calibration blocks, defined by Section XI, Appendix I, Figure 1-3131 or Section V, Article 4, Figure T-434.1. Procedures for exam- ination from the internal surface when not using the full vee should conform to paragraph 3.1.b. below. b. An alternate reflector, other than the 2 percent notch described above may be used provided: 1) that it is located at the clad /base metal interface or at an equivalent distance from the surface, 2) that it does not exceed the maximum allowable defect size, and 3) that equivalent or superior results can be demonstrated. c. The examination procedure(s) should provide for volumetric examin- ation of at least one inch of metal as measured perpendicular to the nominal location of the base metal- cladding interface. 3.2 Scanning Weld-Metal Interface The beam angles used to scan welds should be based on the geometry of the weld/parent metal interface. Where feasible for welds ýsuch as those identified in Section T-441.4.2 of Article 4, Section V of the ASME Code, at least one angle should be such that the beam is per- 1.150-13 pendicular (+ 15 degrees to the