Fusion energy researchin Europe is about to enter a new phase with the global ITER project - intended prove fusion as a technically and economically viable energy source. Developing the maintenance systems for the most critical components of the French built plant is the responsibility of VTT and TUT.
“We have been able to use a transport robot to move a 10tonne reactor element (cassette) along a desired route at an accuracy of around +/- 1mm, and position the cassette in the reactor at a similar accuracy.
"Mechanical flexing in various situations can be compensated so well by the controls that a +/- 1mm accuracy is achievable. The flexing can also be displayed to the operator using a virtual model that matches reality,” says the director of the DTP2 (Divertor Test Platform) project, Acting Research Professor Mikko Siuko from VTT.
“Testing the maintenance work is still in its early stages, and many demanding work phases remain to be tested. The operation is currently being tested on so-called basic cases, after which various possible error situations that could occur in reality will be introduced in stages. The experience gained from the system developed thus far allows us to continue on our chosen path with confidence,” says Siuko.
In the future, the test platform will be expanded, and more work phases and equipment will be included. The system will be expanded with, for example, a transport robot travelling on a circular track inside the reactor. The expansion also allows the addition of various manipulation and connection tasks, and pipe and structural welding.
Central role of remote and virtual technologies
Remote operation and virtual technologies play a central role in the maintenance of the ITER reactor, and provide numerous opportunities for applications in industry. The equipment is being developed and tested using virtual models before the actual prototypes are built.
Various computer simulations can, therefore, be used to ensure that all the systems are compatible with each another, that they can fit into cramped spaces and still work, that the required forces are achieved, and that the flexing remains within allowed limits. Virtual technologies are key to the task design and control of the robots; for example, they are used to replace incomplete camera images and to complement the operator’s senses.
Using augmented reality techniques, parts modelled using a computer or other information can be inserted into the camera image, and the modelled equipment or structure can be viewed in its final operating environment. The progress of the construction or assembly work can be monitored stage by stage.
Virtual prototyping, or digital engineering, makes the equipment R&D significantly faster, and the number of prototypes built can be reduced. Additionally, tasks that had to be carried out sequentially can now be performed in parallel. For example, programming and testing of the control system can be started with a good virtual model.
A massive European test & development environment for remote maintenance systems was commissioned at Tampere in January 2009. In cooperation with other European companies and research institutes, equipment, methodology, software and all digital mechanical engineering segments are developed in tue DTP2 research environment for ITER remote operation needs over coming decades.
The purpose of the Remote Operation and Virtual Reality Centre (ROViR) is to rapidly make available the results of top research in the ITER energy project for use by other industries, in order to improve productivity and competitiveness.
Finland's EU cooperation
Finnish fusion research is integrated into the EU’s fusion research programme through a Contract of Association between Tekes and Euratom. The overall extent of fusion research funded by Tekes is currently around €5m pa, of which Tekes funds around €2m. Finland has participated in the EU fusion research cooperation in nationally selected research areas from the start, amassing special know-how for research and industry.
Due to this, Finnish R&D and industry are in a good position concerning the R&D work required in ITER construction and services, and industrial deliveries and service agreements.
VTT’s research represents roughly half of Finnish fusion research. VTT concentrates on remote maintenance systems with TUT, new welding methods & welding robots in cooperation with Lappeenranta University of Technology, on materials research, magnetic diagnostics (MEMS magnetometers) and first wall diagnostics (smart tiles).
Additionally, VTT participates in Euratom’s fusion experiments (JET and AUG) and performs massive calculations for fusion plasmas and plasma-material interactions. All these areas are very important for ITER construction, safety issues and the future experimental programme.
ITER demands a great deal from new technology, being used to control fusion plasma burning at a Celcius temperature of 100m degrees.
In addition to the EU, Japan, USA, Russia, China, India and South Korea are also participating in the Europe-driven ITER project. Fusion, if successful, will be a real energy option for the future, and significantly contribute to the sustainable energy mix of the future.
Benefits of fusion energy are its almost unlimited fuel reserves and climate friendliness. ITER is also a huge technology development platform in many high-technology fields, increasing the competitiveness of Europe’s technology industry through new expertise.
The global ITER fusion reactor construction has been estimated to cost about €15bn from 2007-2020. Site preparations for the 500MW test reactor are completed, excavations started at Caradache, Southern France. Procurement arrangements for key components (magnets and the vacuum chamber) and architect-engineering contract for buildings have been are signed.
Italian-Russian Ignitor reactor
In a few years, an experimental nuclear fusion reactor near Moscow could be the first to yield a self-sustaining fusion reaction, a milestone for fusion power. (Left)
FTU is a medium-size tokamak machine with a high toroidal magnetic field (80,000 Gauss)
The proposed reactor is based on a design developed by (right) Bruno Coppi, a professor of physics at MIT, and principle investigator on the reactor project with Italy's National Agency for New Technologies, Energy and the Environment. Three similar reactors based on the same design have already been built at MIT.
Italian and Russian physicists have agreed to join forces on the project in April and are now charing a course for the reactor Ignitor.
Ignitor is a doughnut-shaped tokamak reactor device that uses powerful magnetic fields to produce fusion by squeezing superheated plasma of hydrogen isotopes. As electric current and high-frequency radio waves pass through the plasma, heating it to extreme temperatures, the surrounding electromagnetic field confines the plasma under high pressure.
Combined pressure and heat causes the hydrogen nuclei to fuse together to form helium in a process that releases tremendous amounts of heat. In a fully functional fusion reactor, this heat would be used to power an electricity-generating turbine.
The larger, more complex tokamak fusion reactor ITER to be completed in 2019 and ready for full-scale testing in 2026, will be closer to a functioning fusion generator but will not be designed to produce a self-sustaining fusion reaction.
Ignitor is to be a sixth the size of ITER to test conditions needed to produce a self-sustaining reaction. "Ignitor will give us a quick look at how burning plasma behaves, and that could inform how we proceed with ITER and other reactors," says Roscoe White, (left) distinguished research fellow at Princeton Plasma Physics Laboratory.
But Ignitor only tests one key aspect of fusion.
"It will give us information that is important, but it won't give us all the information we need and certainly doesn't replace ITER," Steven Cowley, (right) director of the Culham Centre for Fusion Energy in Oxfordshire, U.K. "It's a demonstration that you can create ignition, but it's not really a pathway to a reactor."
Ignitor's compact dessign doesn't include many real reactor components: as the "breeder blanket," containing lithium and inside the reactor's magnetic coils, provides a continuous supply of tritium, one of two isotopes fused in the reaction. Its high electromagnetic field causes a significant reduction in the conductivity of most superconducting materials so it relies primarily on copper coils to create its magnetic field.
These only operate for short bursts before overheating. So Ignitor can sustain ignition for 4-second bursts. ITER, relying on superconducting coils draws on a larger volume of plasma, amd is designed to maintain peak output for 6 minutes and 40 seconds.