The status of performance demonstration and evaluation developments

It has long been accepted that the inspectors who carry out NDT must be qua lified to ensure they have the necessary competence. However qualification schemes tend to assess general competence rather than the competence needed for a specific inspection. If the latter poses problems beyond those exami ned by the qualification scheme, 'job specific' additions to the basic qual ification are sometimes required. The inspection techniques used in the fie ld usually arise from the involvement of suitably qualified staff in the pr oduction of procedures within the constraints of accepted codes and standar ds. The traditional approach to the provision of confidence in NDT outlined abo ve is perfectly adequate for the majority of inspections. However there are two situations where these measures may be inadequate. The first al-ises w henever the NDT plays a significant role in the demonstration of plant safe ly and the consequences of failure are severe. The second is where the NDT method is new and there are no relevant personnel qualification schemes or standards yet in existence. In these situations, the need to assess and dem onstrate the performance of the NDT techniques applied to specific componen ts is increasingly being required as a necessary precursor to the use of th ose methods. Such demonstrations usually involve the application of the pro posed inspection to test-pieces replicating the components in question cont aining deliberately introduced defects. Exercises such as the PISC series a nd others in the nuclear area showed that there is often a large gap betwee n the performance which is anticipated and that which is actually achieved in practice. This has led to formal requirements in many countries operatin g nuclear plant that the performance of the proposed methods should be show n to match the structural integrity requirements. Some involvement of indep endent third parties in the demonstration process is frequently required Th e need for similar arrangements for the inspection of major components in c onventional plant is currently being considered. A key input to such decisi ons will arise from performance evaluation exercises in which industrial ND T methods are applied to realistic test-pieces. This paper describes the status of performance demonstration requirements f or the nuclear industry worldwide. It also reviews the current position reg arding performance assessment for non-nuclear components.