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:
nd growth rate of flaws. System performance checks to deter- mine the characteristics of the UT system will be made shortly before the UT examinations. Each UT examination will therefore be correlated with a particular system per- formance check. This practice will help to compare results. These determinations will help make it possible to judge whether differences in observations made at different times are due to changes in instrument characteristics or are due to real changes in the flaw size and characteristics. It is recommended that, as a minimum, instrument checks should be verified before and after examining all the welds that need to be examined in a reactor pressure vessel during one outage. Performance of these instrument checks is. likely to add a few thousand dollars to test equipment cost and to take 1 to 2 hours of examination time before and after each reactor pressure vessel (RPV) examination. The examination equip- ment is usually idle between examinations. Performance checks on the examination equipment could be performed during these idle periods. These performance checks are not likely to reduce the number of examinations that a particular UT system could perform in a year. No additional radiation exposure is expected because of this position. 2. CALIBRATION According to this position, system calibration should be checked to verify the distance-amplitude correction (DAC) curve, as a minimum, before and after each RPV examina- tion (or each week the system is in use, whichever is less) or each time any component (e.g., transducer, cable, connector, pulser, or receiver) in the examination system is changed. Subarticle 1-4230, Appendix I, Section XI, ASME B&PV Code (1974 edition), which applied to the inspection of the RPV, required calibration using the basic calibration block at "the start and finish of each examination, with any change in examination personnel and at least every 4 hours during an examination." However, the 1977 rules of Article