What is ITER?

The ITER or International Thermonuclear Experimental Reactor is a joint international research and development project that aims to demonstrate the scientific and technical feasibility of fusion power: a safety source of energy with abundant fuel resources, to meet the needs of a growing world population. The participants are: Republica of China, European Union, India, Japan, Republica of Korea, Russia and United States of America.

Starmakers animation from the ITER oficial website, where other animations are available here. The animation takes a while to download and requires QuickTime.

What is the Nuclear Fusion?

Fusion is the process that powers the sun and the stars. It is the reaction in which two atomic nuclei combine, or fuse, to form a heavier atom. When light atoms such as hydrogen fuse, a lot of energy is released. Fusion is the opposite of nuclear fission, where heavy atoms are split into smaller pieces.

The most suitable fusion fuels on Earth are the Deuterium and Tritium. The current resources of Deuterium and Tritrium are sufficient for millions of years of energy supply. For instance, 10 grams of Deuterium and 15 grams of Tritium would meet the entire lifetime energy needs of a citizen living in a developed country.

Where will be the ITER implemented?

The ITER will be build in Cadarach, south of France. The ITER reactor is installed on a building (the Tokamak Building) with dimensions equivalent to a football field. Another building with similar dimensions provides the infrastructure for maintenance, the Hot Cell Building.

Why Remote Handling?

ITER has no critical negative concerns like fission reactors: no risk of uncontrolled energy release, greatly reduced quantity of high level waste and greatly reduced threat to non-proliferation of weapons material. Please see the differences between fusion and fission.

However, human beings are not allowed o enter in Tokamak Building as soon as the operation starts. A Transfer Cask System (TCS) for the transportation of components during maintenance operations is required. The TCS consists of an unshielded (with respect to gamma radiation) mobile vehicle with dimensions similar to an autobus with a maximum load of 100 tons and moved by air-cushion, provided with autonomous guidance and docking.

Which are the mobile robotics challenges in Remote Handling?

This TCS must be able to travel between different pre-defined start/goals locations in different levels of the Tokamak building. There are several challenges:

• Path planning: optimized set of trajectories from all pairs of start/goal locations in the building (see the examples in the following images). The optimization criteria will consider collision free and smooth paths with the minimization of steering maneuvers and the preservation of a safe area around the vehicle and to accomplish the mission as fast as possible. Additionally it will maximize the length of the commons paths to be followed in different tasks, i.e., different pairs of start/goal locations.
• Path Following: since path planning is accomplished, a control system must drive the TCS through the trajectories, which can be represented by wired system, painted on the floor or simple virtual trajectories.
• Localization: while following the computed trajectories, it is necessary to permanently estimate the position of the TCS for path planning, monitoring and synchronization with the entire system (e.g. vacuum-vessels doors, lift doors, additional TCS or other vehicles).
• Sensor procurement: the particular issue inside the Tokamak building is the radioactive level, which constraints to a reduce spectrum of electronic sensors.
• Experimental results combining several challenges together: develop and test a prototype with similar and huge dimensions, a very unusual motion system (Air-Cushion System) with particular kinematics (Rhombic vehicle).

Opportunities

• 2008 / 10 / 30 - Dissertation proposal for Master Thesis: "Path planning for mobile robot missions in nuclear fusion scenarios of ITER". Download the PDF version here.