| Abstract: | The PISC III Programme involves validation of techniques and procedures and, within this programme, evaluation has now started on the ability to discriminate service induced defects from indications produced by fabrication defects in A 508 Class 2 material when sensitive techniques are used.Action No. 2 of PISC III: Full Scale Vessel Testing is designed for the performance demonstration of three groups of inspection procedures: • - Mechanized ASME type procedures with variable recording level and complementary techniques • - Industrial full ISI procedures (mechanized); • - Several detailed evaluation procedures (generally mechanized) based on advanced techniques to be used on defective areas detected by usual inspection. These procedures, typical for ISI in most of the cases, are applied in four situations which could be typical of old and new LWR pressure vessels: • - vessel material and welds containing important service and fabrication defects but mixed with base material defects and small welding defects; • - nozzle to shell welds with typical service defects, often well isolated and distant from other defective areas in rather clear material and/or welds; • - nozzle inner radius defects; • - artificially heat and unbranched fatigue defects in the test blocks assembled to simulate a PWR pressure vessel wall portion. The paper summarizes the PISC II programme results which stress the characteristics of capable NDT techniques, in opposition to material characteristics like acceptable base material defects. It describes the full scale pressure vessel components available to conduct the PISC III exercise with improved ultrasonic techniques. |
