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ITER future and DEMO

The construction and operation of ITER is a complex, long-term project that marks a significant step along the road to a very specific goal: the attainment of fusion power. This long view of the future is a characteristic of the development of fusion energy science and technology that has shown continuous progress while overcoming significant issues

Beyond ITER

To follow ITER the efficient large-scale production of electricity from fusion and the demonstration of tritium self-sufficiency will be required before commercial fusion power stations can be designed and built.


The successful construction and operation of ITER will be a significant step towards sustainable fusion energy production from fusion. The information, technologies and experience provided by ITER will be crucial to the development of a demonstration power plant (DEMO). The first commercial fusion power plants are set to be established following DEMO.

ITER will prove many of the components required for DEMO. In parallel, advanced fusion materials research will contribute the new materials solutions that will be essential for successful operation of a fusion power plant.

In Japan the International Fusion Materials Irradiation Facility (IFMIF) project has started. An IFMIF facility will be able to test advanced fusion materials in environments that mimic those inside a fusion power reactor.


DEMO will generate significant amounts of electricity over extended periods and will be self-sufficient in tritium. It will be designed to produce up to 500 megawatts of electricity which will require a thermal output of around 1500 megawatts. If DEMO is built at roughly the same size as ITER, it will require much higher heat flux through the reactor walls and improved plasma performance.

Research suggests that this performance could be achieved with a 15 % increase in ITER's linear dimensions, and a 30 % increase in the plasma density.

A major challenge will thus be the performance and durability of the breeder blanket technology, and the systems for refuelling and replacing reactor modules during operation.

If DEMO is successful in terms of systems and performance, the DEMO reactor itself could be used as the commercial prototype, creating a 'fast track' to fusion power, perhaps knocking 20 years off the time for the first commercial fusion power to reach the grid.

Commercial fusion Power

The final step will be the construction of a first-of-a-series commercial-sized fusion power reactor. To achieve twice the electrical power output of DEMO (i.e. 1000 megawatts) only a slight increase in reactor size would then be required.