Siemens Nuclear, now part of Framatome ANP, has supplied Finland’s Loviisa plant with their latest steam generator inspection manipulator. In 1992, Siemens had supplied the first steam generator inspection manipulator for Loviisa. Since then Siemens has been performing inspections on the steam generators of the two VVER-440 units.
The inspection manipulator is used for remote-controlled positioning of various modules for the performance of in-service inspections in the steam generator headers. It is inserted in a fully-assembled state into the header with the aid of the reactor building crane, and can be easily moved from there to the next header without the need for any assembly work.
The header inspection manipulator is equipped with a dual pusher unit for eddy current testing of steam generator tubes. It enables the eddy current probe to be moved inside the tubes over their entire length. The dual pusher unit comprises two independent equipment units that can be combined with each other with the aid of appropriate adapters. Two adjacent tubes can thus be tested simultaneously, which means that the time required for testing is halved by comparison with a single pusher unit.
A major advantage is the off-centre arrangement of the mast. Since the centre of the header remains free, the probe pusher unit or the tube repair modules can be positioned there. The redesign of the mast support also makes it possible to remove the pusher unit completely from the header and thus makes it freely accessible. Due to the fact that it is equipped with a quick-release coupling system to accommodate the inspection and repair equipment, equipment changeover and adjustments to the eddy current testing systems are possible within a very short space of time.