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:
t and greater of the through-wall thickness of the vessel wall measured from the inner surface should be recorded in accordance with the requirements of ASME Section XI and characterized at 50 percent DAC. c. Reflectors which are within the inner 25 percent of the throughwall thickness should be recorded at 20 percent DAC. Characterization should be in accordance with the demonstrated'methods under paragraph 6.0. Where the indication is sized at 20 percent DAC, this size may be corrected by subtracting the beam width in the through-thickness direction obtained from the calibra- tion hole (between 20 percent DAC points) which is at a depth similar to the flaw depth. If the indica- tion exceeds 50 percent DAC, the length should be recorded by measuring the distance between 50 percent DAC levels. The determined size should be the larger of the two. 6.3 Indications without Changing Metal Path a. Indications which do not change metal path distance when scanned in accordance with the requirements of ASME Section XI and are within the outer 75 percent of the through-wall dimension should be recorded when any continuous dimension exceeds one inch. 4 1.150-14 b. If the indication falls within the inner 25 percent of the through-wall I dimensions, it should be recorded at 20 percent DAC and evaluated at 50 percent DAC. c. Precautionary note: Indica- tions lying parallel to welds may .appear as nontraveling (without changing metal path) when scanned by parallel moving transducers whose beams are aimed normal to the weld, ie. at 9Q0*. Multiple scans, however, may reveal that these indications are traveling indications. If so, recording and sizing are to be done in accordance with paragraph 6.2. 6.4 Additional Recording Criteria The following information should also be recorded for indica- tions that are reportable according to this regulatory position: a. Indications should be recorded at scan intervals no greater than Ione-fourth inch. b. The recorded information should