Source: EUROfusion; CC BY 4.0 licence.
The DEMOnstration power plant, DEMO, will be ITER's successor. With the transition from ITER to DEMO, fusion will go from a science-driven, lab-based exercise to an industry-driven and technology-driven programme. A key criteria for DEMO is the production of electricity although not at the price and the quantities of commercial power plants. Laying the foundation for DEMO is the objective of the EUROfusion Power Plant Physics & Technology (PPPT) Work Programme.
Current fusion experiments were primarily designed to investigate plasma physics. However, DEMO must demonstrate the necessary technologies not only for controlling a more powerful plasma than has previously existed, but for safely generating electricity consistently, and for regular, rapid, and reliable maintenance of the plant. The design of such a plant must take account, not just of physics requirements, but also of engineering and technological limitations.
DEMO & the Roadmap
Building and operating DEMO, which will hook fusion electricity to the grid, is the subject of the last phase of the EUROfusion Roadmap.
While the central requirements for DEMO lie in its capability to generate between 300 Megawatt to 500 Megawatt net electricity to the grid and to operate with a closed fuel-cycle, meaning spent tritium fuel will be reprocessed, the PPPT team is looking at requirements that will lay the foundation for a robust conceptual design:
- Selecting the right breeding blanket. Blankets are the internal components of the reactor wall that absorb the energy from the fusion reaction, ensure the tritium breeding process and shield the components outside the reaction chamber from the fast fusion neutrons.
- Selecting the right divertor concept.
- The right design for the first-wall, the innermost lining of the reactor wall, and its integration into the blanket must take into account that the first-wall might see higher heat loads than assumed in experimental settings.
- Selecting the minimum pulse duration of DEMO and of the corresponding mix of plasma heating systems.
- Designing in a way that all maintenance work can be carried out remotely via manipulators.
- Incorporating nuclear safety issues from the very beginning of conception.