Development of lower manipulator system for breeding blanket maintenance within large port-based tokamaks

Large port-based tokamaks for energy production are expected to be developed around breeding blanket technology, the purpose of which is to breed Tritium, provide shielding to the vessel walls, and carry heat transfer loops. These blankets are expected to be split into five segments in every torus section [1], each weighing up to 60 tons, and will require periodic replacement through the Upper Port for maintenance. During replacement, the blankets need to be guided in the vacuum vessel through highly restricted kinematic paths to avoid collisions. A Two Port Remote Handling approach is therefore being investigated. In this approach, the Lower Manipulator System (LMS) is expected to operate through the Lower Port to guide the blankets and react to the severe loads arising from the offset between the blankets' Centre of Gravity (CoG) and the lifting point. Several mechanisms for the LMS have been developed to comprehensively explore blanket handling capabilities using this approach. This paper presents the different LMS concepts and discusses the respective salient features.