Mini-invasive robotic diagnostics for fusion machines

On fusion experimental reactors, in-vessel remote operations will be mandatory to allow maintenance interventions and limit personal radiation exposures. In addition, mini-invasive robotics inspections will be required between plasma pulses for safety issues management or to assist the scientific programs. These remote-controlled devices will have to offer good availability and reliability levels while keeping the facility conditions required for plasma operations. CEA laboratories have developed a robot prototype called Articulated Inspection Arm (AIA) for mini-invasive inspection of Plasma Facing Components (PFC). This capability was demonstrated at the end of 2008 by remotely inspecting the plasma vessel of Tore Supra facility without breaking Ultra High Vacuum (10-6 Pa) and temperature conditioning (120°C). After this premiere, numerous applications have been identified and CEA, with industrial partnership, initiated studies of embeddable diagnostics for assisting tokamaks operation. These developments cover wide fields such as safety with PFC viewing movie-camera, radioactivity measurement, dust management, scientific missions related to PFC behavior monitoring or diagnostics calibration and plant availability with routine vessels inspections and leak localization devices. Preliminary analyses are presented and results obtained with gas leak localization probes are described in the paper. In particular, experimentations performed under vacuum conditions demonstrating leaks sensibility and reactive response signals as a function of the distance between the remote detectors and the leaking components are presented.