Evaluation of the Sizing Results of 12 Flaws of the Full Scale Vessel Installation

(abstract only) From 1974 to 1986 the PISC II programme (Programme for the Inspection of Steel Components) results were discussed by a group set up by the PISC II Management Board. This group called Programme Elaboration Group considered two major conclusions of PISC II. 1. Inspection Procedures of Pressure Vessels as evaluated on the basis of the Assembly Nr3 of PISC II appeared to contain the necessary features for the assembling of effective inspection procedures of reactor pressure vessels. 2. Sizing techniques results, as evaluated in PISC II on the basis of the inspection results of selected flaws in the PISC II assemblies were generally judged not to be effective or not to demonstrate trends of improvement when compared with the usual 6 dB drop techniques used in the standard industrial techniques. Indications were present however of efficient techniques based on advanced techniques but computer reconstruction algorithms often conducted to confusion between flaws, texture and other metallurgical features. At the end of the exercise (1986) the Referee Group of PISC was able, through direct cooperation with teams of the sizing exercise, to demonstrate that a large part of the errors were due either to human factors or to scanners limitations and not to the intrinsic features of the ultrasonic methods used