Lessons Learned From ET and UT Qualification in Phare Project 1.02/95
L. Horácek, Nuclear Research Institute, Czech Republic; J. Shejbal, P. Tkadlcik, Dukovany NPP, Czech Republic
ABSTRACT
Phare project PH 1.02/95 "In-Service Inspection of Steam Generator Collector" (1998-2001), presented in the paper, was devoted to the qualification of NDT systems for automated UT and ET examinations of VVER 440 type steam generator collector thread holes. The project, completed in June this year, covered the development of manufacturing technology for stress corrosion cracks, the Round Robin Test (RRT) for UT and ET conducted by regional teams on the fabricated test assemblies with intended defects, development and optimisation of inspection procedures, elaboration of technical justification for UT and ET techniques and practical trials. The manufacturing technology for SCC type of defects (predominantly intergranular stress corrosion cracks) in threads and thread hole cups has been developed by VTT Finland, the leader of PH 1.02/95 consortium. The two test assemblies manufactured as segments with four and five thread holes from original VVER 440 steam generator collector were equipped with intended SCC type of defects and EDM notches of various dimensions, types and shapes. One thread hole in the test assembly has been used as a calibration block. The RRT was performed as a blind test for one UT team and two ET teams on the fabricated test assemblies with intended defects and supervised by NRI Rez staff. The NDT data and results were assessed by the reference laboratory JRC Petten, one of the Western subcontractors of the PH 1.02/95 consortium. Based on the results of the RRT the inspection procedures were improved and optimised within laboratory trials on the test assemblies where additional needed SCC and EDM types of defects were manufactured. The progress in inspection procedures and NDT systems capabilities and effectiveness has been proved within practical trials and the qualification objectives have been met. The practical advantages following the ENIQ qualification methodology in the project are outlined and highlighted in the paper. Lessons learned from the development of manufacturing technology of SSC type of defects, RRT, elaboration of the technical justifications and inspection procedures for ultrasonic and Eddy current automated inspections, optimisation of inspection procedures, laboratory and practical open trials are summarised, as well. The project proved both methods Eddy current and ultrasonic testing as very effective for automated inspections of steam generator collector thread holes.
Publication Source: 3nd International Conference on NDE in Relation to Structural Integrity for Nuclear and Pressurized Components, November 14-16, 2001, Seville Spain. Publisher: Tecnatom s.a. - [Homepage]
