Assessment of a water hydraulic joint for remote handling operations in the divertor region

Due to the high level of radiations, all the nominal maintenance in the divertor region of ITER will be carried out with help of robotic means. Due to their high power/weight ratio, hydraulic actuators are interesting in space constrained areas. Pure water is the only fluid medium able to ensure the cleanliness requirements of ITER during maintenance operations. Although basic hydraulic elements like pumps, on–off valves, filters running with pure water are already available on the market, actuators are not so many and generally limited to linear motions.Starting from the standard oil hydraulic Maestro arm, a six-degrees-of-freedom hydraulic manipulator manufactured by Cybernetix and used in decommissioning activities, CEA LIST redesigned for water applications the elbow vane actuator of the arm.Servovalves are essential components of the joint's control loop. To improve performance, stability and safety of the force control loop, CEA LIST launched the development of a pressure control servovalve fitting the space constraints of the Maestro.Both performances of the modified vane actuator and of this new servovalve are presented in this paper.