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:
ld recommend, for the first time, that indications with significant length of indication travel (larger than the standard calibration holes) or with significant depth dimensions be recorded. It is not expected that the slag type of flaws, which are common among welds, or geometric reflectors will give signif- icant traveling indications within the guidelines pro- posed. Hence, no substantial increase in recorded indications as a result of this recommendation is expected; however, the exact increase is difficult to predict or estimate. Reporting of indications associated with flaws larger than 1 inch (indications larger than 1 inch plus beam spread at 20 percent DAC level) is also new. RPV welds are examined by radiography, and no flaws larger than three-quarters of an inch are acceptable in these welds. Because of this acceptance length, only new service- induced flaws larger than 1 inch, of which there should not be many, are expected to be identified and reported as a result of this recommendation. Because of the above two new reporting recommenda- tions, there may be an increase in examination time and dollar cost that is difficult to estimate. This will depend on how many significant flaws are detected and how large and complex they are. 4 1.150-18 c. Radiation exposure 2.3 Comparison of Technical Alternatives Recommendations of this guide apply to the examina- tion of RPV welds and RPV nozzle welds. RPV welds are usually examined by automated equipment, and data are collected on tape. Therefore, no increase in radiation exposure is anticipated as a result of the regulatory guide positions addressing RPV weld examinations. RPV nozzle welds are sometimes examined by automated equipment but in most cases by manual UT. An increase in radiation exposure to examination personnel may be expected while RPV nozzles are being manually examined. The probable percent increase in examination time or radiation exposure is impossible to estimate without field data and