This paper reports on a study of the existing or proposed maintenance arm systems with similar functions and structure to that of the proposed DEMO Multi-Purpose Deployer (MPD).The current MPD design iteration consists of a boom deployment system that is ~30m long and can support a payload of ~1000kg, while still being able to access the DEMO vacuum vessel through a 2.78m high by 1.08m wide port. The purpose of this work is to benefit from previous experience by collecting and comparing the mechanical attributes and performance of these systems as well as their advantages and disadvantages and any issues encountered to bring design input to MPD design development.
The following systems were investigated:
- JET in-vessel remote handling booms;
- JET ex-vessel Telescopic Articulated Remote Mast (TARM);
- NET Experimental Device for In-Torus Handling (EDITH);
- Tokamak Fusion Test Reactor (TFTR) Maintenance Manipulator;
- Fukushima Boom Arm;
- Snake-like Robot Arms for Nuclear Environments.
- Systems that are currently in development for ITER and CFETR
The paper concludes that these systems, comprising of articulating links to form long-reach slender structures, give rise to challenges with their payload, stiffness, and control. The systems with high payload capacities have structures consisting mostly of planar boom links that act in the horizontal plane in order to support and manoeuvre the high vertical loads. These planar systems all have links that consist of thin-walled rectangular section beams, but the joints of these systems showed considerable variation in design of both their structure and driving mechanisms. Several of the systems had design solutions that improved the accuracy and repeatability of the systems, importantly also including several design aspects to reduce the detrimental impact of the high radiation environment found within fusion vacuum vessels.
This work has been carried out within the framework of the EUROfusion Consortium and has received funding from the Euratom research and training program 2014-2018 and 2019-2020 under grant agreement No 633053. The views and opinions expressed herein do not necessarily reflect those of the European Commission.