The PIONEER 4 manipulator moves on two rings which are temporarily installed in the Reactor Pressure Vessel. Probe systems for different inspection tasks are changed by remote control under water to minimise inspection time. The PIONEER 4 combines high rigidity of the system with excellent positioning accuracy. Modern Ultrasonic and Eddy Current data acquisition systems and online evaluation on the basis of digitised HF data provide maximum information about integrity of the Reactor Pressure Vessel.

The PIONEER 4 design allows parallel inspections using two complete systems, thus cutting down the inspection/assignment time by 50 % while offering a higher inspection quality and full accessibility of the reactor pool. The realistic inspection time for a typical German 1.300 MW Reactor Pressure Vessel including separate scans for transverse and longitudinal flaws due to tandem technique is three days.