The present technology of Inservice Inspection of the BWR RPVs in Germany is characterised by:

Permanently installed vertical tracks allow for a complete coverage of all shell and nozzle weld areas as well as nozzle inner radii. This coverage is achieved by a relatively complex manipulator with different extension modules for the different scanning areas.

The inspection techniques encompass high angle longitudinal dual element technique, 45° and 60°-pulse echo as well as the tandem technique specifically targeted for eventual embedded perpendicular defects. This means a number of complex probe systems requiring double, in cases of nozzles even quadruple scanning in order to achieve full coverage with the different techniques.

This status of technology was associated with the need to distribute the entire ISI scope over two to three outages. The new RPV inspection concept reduces the schedule considerably by combining advanced UT phased array technology with innovative robotics in order to arrive at an integrated system approach. The new manipulator concept utilises the newly developed modular robot drive units with integrated microelectronics for control and power supply. This means a reduction in weight and an increase of manoeuvrability and handling efficiency. The O. D. manipulator can operate on vertical as well as on horizontal tracks. The PC-control system allows for a large variety of continuous path motions combining a number of different drives into one scanning movement. Parts of this concept can also be transferred to RPV inspection from the I. D. surface as well as for the UT-examination of the core shroud. The I. D. ISI concept consists of two independently operating systems using a vertical arm for the upper part of the RPV above the core shroud. The second system using a vertical telescopic arm facilitates scanning in the narrow annular gap between core shroud, respectively jet pumps and the I. D. vessel wall. This second system can also cover the inspection of the core shroud utilising a different front-end module.

For both applications, the inspection from the O. D. and from the I. D. surface, the UT probe system design takes full advantage of the phased array capabilities combined with state of the art probe building. In order to ensure complete coverage, a probe system consists of four to five probes. By vertical angle variation, each of the first four probes combines all necessary angles of incidence. For the O. D. inspection, the fifth probe with lateral skew is dedicated to the examination of the nozzle inner radius.

The SAPHIR system consists of state of the art UT-instrument and data acquisition and processing station allowing to operate phased array and standard UT-probes simultaneously. The software features are optimised for assisting in the data analysis process and provide different modules in terms of raster scan, sector scan, defect reconstruction and other detection, discrimination and sizing packages combined with field proven documentation features.

The complete system has undergone extensive successful trials in the framework of qualification in Germany as well as within PDI and VIP.