Remote maintenance considerations for ITER [International Thermonuclear Experimental Reactor]

The International Thermonuclear Experimental Reactor (ITER) is being designed as an ignition machine with a long active phase that will result in high radiation levels and the need for a high degree of remote maintainability. The machine must be designed such that recovery is possible from any credible failure. Also, ITER is experimental and therefore will likely undergo many modifications in the course of its mission. These must be performed remotely. The objectives of ITER cannot be realized without an effective remote-handling and maintenance capability. This paper discusses the basic ITER remote maintenance requirements, the remote-handling equipment concepts, and the challenges that must be addressed to obtain a degree of maintainability never before attempted on a fusion machine. The ITER machine is being designed in a modularized fashion to permit the replacement of any module by the remote-handling systems. Each module will be characterized as to its expected failure rate. The modules with the highest expected failure rate, such as divertor modules, will be given highest priority as to ease of remote replacement. This hierarchial approach will be applied to all modules, down to and including those modules with low expected failure rates such as poloidal field coils