ULTRASONIC INSPECTION OF COMPLEX-GEOMETRY COMPONENTS FOR THE SIZEWELL-B PRESERVICE INSPECTIONS

Sizewell B, the first British PWR, is nearing completion and the prima ry and secondary circuits are undergoing extensive pre-service inspect ion. OIS is carrying out the inspection of the Incredibility Of Failur e (IOF) and Class 1 components. These are nearly all automated inspect ions and many of the components are austenitic. The NDT Applications C entre of Nuclear Electric has provided its MIPS and GUIDE automated ul trasonic inspection software systems for these inspections. The high q uality of inspection required for Sizewell B has required the developm ent of novel manipulators, particularly for the complex geometry compo nents such as the 45-degrees branch nozzle, to enable the necessary ul trasonic coverage to be achieved. Some of these manipulators have four axes of motion and the MIPS software has been enhanced to enable the required complex scan patterns to be achieved. The precise plotting of ultrasonic data provided by MIPS and GUIDE has enabled the methods su ccessfully deployed by Nuclear Electric during the PISC II trials to b e implemented for these site inspections. Many of the inspections are subject to independent validation by the Inspection Validation Centre operated by AEA Technology. This paper describes the inspection system developments which have been undertaken and reviews the experience to date in performing these inspections.