ML25016A280
| ML25016A280 | |
| Person / Time | |
|---|---|
| Issue date: | 01/22/2025 |
| From: | Stephen Cumblidge, John Honcharik, Carol Moyer NRC/NRR/DNRL/NVIB, NRC/NRR/DNRL/NPHP |
| To: | |
| References | |
| Download: ML25016A280 (1) | |
Text
NRC Perspective on Ultrasonic Testing in Lieu of Radiographic Testing Stephen Cumblidge, Carol Nove, John Honcharik 2025 Industry/NRC NDE Technical Information Exchange Public Meeting
Bottom Line Up Front
- The NRC is not opposed to the use of UT in lieu of RT for new construction if a UT process is shown to provide an acceptable examination with the ability to review the data in the future the NRC
- Appropriate Acceptance Criteria are Needed 2
Challenges with UT in Lieu of RT
- UT effectiveness can be degraded (sometimes very severely) by different materials, weld surface and single sided access
- There is no common format for encoded UT data
- Differences in acceptance criteria and ability to characterize flaws From NUREG/CR-7204 Applying Ultrasonic Testing in Lieu of Radiography for Volumetric Examination of Carbon Steel Piping 3
NUREG/CR-7204 Highlights Detection Reliability - Implanted flaws in carbon steel piping UT and RT appear to have similar detection capability for volumetric flaws
- UT missed 1 small porosity (5.3 mm (0.2 in.)
in length)
UT has a better detection capability for planar flaws
- RT missed 5 planar flaws
- Planar flaws are more likely to grow throughout the service lifetime of the plant and could be more detrimental 4
- UT is more effective at finding planar flaws including small planar flaws
- RT is better at finding small volumetric flaws such as porosity
- For flaws detectable by RT, flaw discrimination is relatively easy
- While possible, it can be very challenging for UT procedures and personnel to distinguish between different flaw types 5
Acceptance Criteria ASME Code Section III allows small volumetric flaws such as porosity and slag but not lack of fusion or cracks Operational experience has shown that small embedded cracks and LoF are relatively benign, but inner diameter repairs are associated with service-induced cracking Using UT in lieu of RT with Section III RT Acceptance criteria may result in more repairs that do not improve the quality of the final weld UT-Specific Acceptance Criteria are likely needed 6
Recent History with UT in lieu of RT
- The different revisions of ASME Code Case N-659 were not approved by the NRC
- The experience with applying UT in lieu of RT were used to develop ASME Code Case N-831 and N-831-1 7
What Changed from N-659 to N-831-1?
- Improved technical basis for UT
- Industry experience with proposed alternatives
- Public meetings and ASME Code week discussions describing the progress
- Performance demonstration for the UT personnel, equipment, and procedure
- Improved technology-Phased Array being available instead of two angle beams 8
- Criteria necessary
- Performance demonstration (detection, sizing, and full volume exam)
- Flaw characterization or other means of differentiating flaws for acceptance (false calls vs undersizing)
- Requirements for encoding
- Acceptance criteria 9
Can the Section III Exam be used as the Pre-Service Exam?
- The Acceptance examination and the pre-service examinations do different jobs
- Acceptance examination is to ensure quality workmanship
- Preservice exam is to provide an as-installed examination and serve as a baseline for future examinations 10
Path Forward
- The NRC staff are open to combining the pre-service and acceptance examinations, but acceptance would be based on the details
- As an example, the pre-service examination be required to meet or exceed ASME Code Section XI Appendix VIII requirements
- Be performed on installed welds
- The examinations be encoded and recorded for future reference
- Robust acceptance criteria to ensure weld integrity (previously RT and UT performed since they are complimentary) 11
Questions?
12