Scientists and engineers took a good look at the current status and future challenges of fusion research during a “EFDA Technical Meeting: status of DEMO achievements under EFDA”. Nearly one hundred participants, representing 17 European laboratories, EFDA, ITER and F4E as well as some industrial enterprises, met in Garching on September 29th and 30th to prepare the ground for a DEMO conceptual study. They had a lot of material to work through: Between 2000 and 2008 EFDA has supported 70 tasks directly aimed at DEMO. In addition, a number of other EFDA-tasks included DEMO-related research. In excess of 124 scientists from nearly all European Associations were directly responsible for DEMO-related EFDA tasks, with many more researchers involved as co-workers. It was now time to take stock of the results and derive guidelines for further work on DEMO. The meeting has indeed resulted in a useful set of information for a European DEMO advisory group which has the task to make proposals on future DEMO activities in Europe to the CCE-FU (Euratom Consultative Committee on Fusion) and F4E.

DEMO poses manifold challenges for fusion research. Stable scenarios for such powerful plasmas are not yet available. Suitable heating and current drive systems as well as control tools need to be developed beyond their present capabilities. DEMO will also need blankets that breed tritium at a rate which ensures self sufficiency. The very large flux of fast neutrons, which will be produced by the plasma, calls for wall materials with very low activation rates in order to keep the production of nuclear waste as low as possible. ITER is expected to deliver a number of key answers for many of the issues mentioned above, but not all. Therefore ITER needs to be complemented by an accompanying programme towards DEMO, a programme that needs to be very thoroughly defined.

A number of urgent issues to be assessed were pointed out at the meeting:

• The options for the DEMO plasma scenario will strongly depend on the solutions available for handling steady and transient power loads, mainly on the divertor. The most urgent open questions are with regard to the mitigation and / or avoidance of disruptions and ELMs, the power fluxes on the divertor plates and the behaviour of impurities eroded from the plasma facing materials. To limit power fluxes to the divertor plates, the plasma has to radiate higher levels of heat, therefore spreading the heat load in a larger area. This could be the main challenge for plasma scenario development.

• Many current diagnostic techniques are not suitable for DEMO’s harsh environment and thus new methods must be developed. Rather than the sophisticated scientific instruments they are today, diagnostics on DEMO must be designed as simple and reliable tools, providing the plant operator with all necessary information in a practical and straightforward way,.

• To meet DEMO requirements, technological R&D can be undertaken independently from most physics and plasma operational issues. The development and design of fundamental subsystems such as breeding blankets, heating and current drives for profile control, high temperature (>500 °C) cooling as well as remote handling and maintenance systems should be pursued vigorously, since they require challenging long-lead developments.


DEMO is part of the European fast track to fusion which started with the construction of ITER and will precede the construction of a commercial fusion power plant. DEMO will be built to demonstrate and optimise the operation of a fusion reactor capable of producing electricity. It will provide an integrated demonstration of all the required technologies in reactor operating conditions. DEMO is intended to supply several hundred MW of electricity in a more or less continuous operation. It will operate on deuterium-tritium fusion reactions. Tritium will be bred from lithium in dedicated breeding blankets surrounding the plasma.

The participants of the meeting concluded that keeping the ‘European fast track’ requires greater research efforts than today. They consider it vital to keep the design of DEMO flexible enough to incorporate new results as they come. Many insights may come at a later date, as DEMO construction is foreseen to start around the end of ITER’s first experimental phase, i.e. about 10 years after ITER’s first plasma. To prepare for DEMO, it is essential for Europe to get all key tools operational: ITER, a materials irradiation facility – the IFMIF project, as well as an accompanying (or satellite) tokamak programme.

Participants therefore felt that it is time for the previously mentioned DEMO advisory group to define more precisely the objectives and mission of DEMO in order to design an integrated, complete, relevant and consistent programme for physics and technology R&D. When resources will become available, the DEMO conceptual design activity – encompassing design and R&D – should start with ambitious but realistic targets. The preparatory steps that start now are essential for the success of DEMO, the step after ITER that will mark the entry of fusion into the energy production era.

Thanks to Vincenzo Pericoli, EFDA, for his input

All presentations given at the meeting can be found on the EFDA website: