A breakthrough in nuclear fusion could solve many supply problems through almost limitless energy generation. However, technical implementation remains complex and key technological building blocks are still missing for the practical operation of future power plants. To change this, the Karlsruhe Institute of Technology (KIT) is now developing the first integrated fuel cycle for stellarators together with partners from science and industry.

Fusion energy: a beacon of hope

For a long time, power plants with fusion reactors have been seen as a beacon of hope for a clean energy future. “In recent years, spectacular progress has been made in the generation and handling of fusion plasmas,” says Dr. Thomas Giegerich from the Institute for Technical Physics (ITEP) at the KIT. “However, many questions of practical operation remain unresolved.” This applies, for example, to the fuel cycle in stellarators, a type of reactor in which the plasma is confined in a twisted magnetic field in such a way that continuous operation is possible. ‘So far, there is no concept for handling the fuel in a future fusion power plant,’ emphasizes Giegerich. “There is also no facility with which such a fuel cycle could be validated.” Both are now to be realized in the KIT-coordinated project SyrVBreTT (which stands for: Synergy Network Fuel Cycle and Tritium Technologies) in a consortium directly with industry.

Integrated development of the fuel cycle

Fusion power plants require a mixture of the hydrogen isotopes deuterium and tritium as fuel, which is converted to helium in the reactor. To prevent the helium content in the fusion plasma from rising too sharply, the reaction mixture in the stellarator must be continuously pumped out, cleaned and then re-injected together with new fuel. The entirety of the systems required for this is referred to as the inner fuel cycle. Because the tritium needed for the fusion reaction does not occur naturally due to its short half-life of a few years, it must be produced technically in so-called breeding blankets. All the systems required for this are referred to as the external fuel cycle. “In our project, we are developing the technical components necessary for both cycles, such as pumps, storage beds and pellet injection systems,” says Giegerich.

Technologies to be validated under realistic conditions

In order to avoid interface problems with the individual components, the inner and outer fuel cycles are being developed together and in coordination with each other. In addition, targeted simulations and experimental investigations are to ensure that the technologies can be validated under realistic conditions. “At KIT, we are building a Fuel Cycle Test Facility for this purpose, in which all relevant systems can be tested under real conditions,” says Giegerich. This is a crucial step in enabling the transition from experiment to practical application.

About SyrVBreTT

The SyrVBreTT project is coordinated by KIT. The following partners from science and industry are involved: Forschungszentrum Jülich, Gauss Fusion, Kyoto Fusioneering Europe GmbH and the University of Stuttgart. SyrVBreTT is initially set up for three years and is funded by the Federal Ministry of Education and Research with 17 million euros. This includes 4.8 million euros in funding directly for KIT.

Video