From Technical Specification to Examination results: The Story of Qualification for Belgian RPV Inspection

摘要

In 1992, Electrabel, the Belgian utility, decided to use new qualified procedures for all mandatory In-service Inspections. For the Reactor Pressure Vessel, the qualification process was conducted through a close collaboration between the vendor (Intercontrole) and a technical group formed by Electrabel (the Owner) and Tractebel Energy Engineering (the Architect-Engineer), under review by the Belgian Safety Authorities. The whole qualification process, performed in an industrial context, has shown the importance of various aspects: a review of the construction files and of previous ISI results; a detailed definition of the inspection objectives (defects to be detected and level of characterization); a systematic verification of the NDE procedure performance, for each objective or situation; the feedback from site experience on procedure and qualification optimization; and a multi-disciplinary approach. The paper presents how the initial inspection requirements and the methodology of qualification were specified, by combining the rules of the ASME XI code and the European Methodology for Qualification. It shows that the NDE procedures have been systematically improved during the qualification process and how the procedure performance and limitations have been determined and demonstrated by an adequate combination of tests on blocks and technical justification. To conclude, the paper also states the lessons learnt from the first on-site experience of Reactor Pressure Vessel ISI with qualified NDE procedures.