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:
e taken to ensure that the different variables such as temperature, vibration, and shock limits for which the EBS error band is determined are not exceeded during transport, use, storage, etc. d. When a universal calibration block is used and some or all of the reference holes are larger than the reflector holes at comparable depths recommended by Article 4, Sec- tion V, of the ASME Code, 1980 edition, a correction factor should be used to adjust the DAC level to compensate for the larger reflector holes. Also, if the reactor pressure vessel has beenpreviously examined by using a conventional block, a ratio between the DAC curves obtained from the two blocks should be noted (for reference) with the significant indications data. 3. NEAR-SURFACE EXAMINATION AND SURFACE RESOLUTION The capability to effectively detect defects near the front and back surfaces of the actual component should be estimated. The results should be reported with the report of abnormal degradation of reactor pressure boundary in accordance with the recommendation of regulatory posi- tion 2.a(3) of Regulatory Guide 1.16. In determining this capability, the effect of the following factors should also be considered: a. If an electronic gate is used, the time of start and stop of the control points of the electronic gate should be related to the volume of material near each surface that is not being examined. b. The decay time, in terms of metal path distance, of the initial pulse and of the pulse reflections at the front and back surface should be considered. c. The disturbance created by the clad-weld-metal interface with the parent metal at the front or the back surface should be related to the volume of material near the interface that is not being examined. d. The disturbance created by front and 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