An ITER Relevant Robot for Remote Handling : On the Road to Operation on Tore Supra

In the context of Fusion, several experimental reactors (such as the International Thermonuclear Experimental Reactor (ITER)), research aims to demonstrate the feasibility to produce, on earth, the plasma that occurs on the sun or stars. Fusion using magnetic confinement consists in trapping and maintaining the plasma in a magnetic container with torus shape (Tokamak), under Ultra High Vacuum (10-6 Pa) and high temperature (100 millions °K). During plasma burning, the severe operating conditions inside the vacuum vessel apply high thermal loads on the first wall Plasma Facing Components (PFCs). Therefore, regular inspections and maintenance of 100% of the first wall surface is highly required. When considering the maintenance between two plasma shots, the conditions to perform maintenance tasks, without breaking the vacuum, exclude human intervention and require use of remote means based on robotic technologies that enable extension of human capabilities into the machine. The technologic research on robotics and remote operations is called the Remote Handling (R.H.) activity. The Interactive Robotics Unit of CEA-LIST has been working on Remote Handling for Fusion for more than ten years. Experience on JET reactor maintenance has proven the feasibility to maintain an installation with robots controlled by distant operators (A.C. Rolfe et al., 2006), (O. David et al., 2000). When considering generic Tokamak relevant conditions such as we can find in the CEA Tore Supra Tokamak, the set of major challenges we selected for the Remote Equipment is to sustain the following severe operating conditions: ultra high vacuum (10-6 Pa), temperature (120°C), baking (200°C). The limited number of machine access ports and the very constrained environment complicate the introduction of a robot into the machine. These issues impose an major step in term of technologic research for R.H.: innovation in robot conception, new kinematics, new actuator technologies, hardened electronic components were designed, simulated and tested to cope with the ultra high vacuum and the temperature constraints. Since 2000, under EFDA (European Fusion Development Agreement) support, the Interactive Robotics Unit of CEA-LIST and the CEA-DRFC of Cadarache collaborate on a potential ITER relevant Remote Handling Equipment (RHE). The main challenge of the project is to demonstrate the feasibility of close inspection of a plasma chamber In Vessel