Fusion research is a major global project with ambitious goals: controlled nuclear fusion is to be established as a virtually inexhaustible, safe, and climate-friendly energy source. After decades of intensive basic research, demonstration plants and initial commercial concepts are increasingly coming into focus.

Fusion involves light atomic nuclei (typically deuterium and tritium) merging to form a heavier nucleus, releasing a great deal of energy in the process. This produces significantly less radioactive waste than nuclear fission. Around the world, various research institutions and, increasingly, companies are driving the further development of different fusion concepts. Technically, nuclear fusion concepts differ mainly in how the high-temperature fusion plasma (>10⁸ K) is confined. They rely either on strong magnetic fields (tokamak and stellarator) or on the inertia of the imploding fuel (inertial fusion/laser fusion). The most important international projects currently include: ITER (EU, China, India, Japan, Korea, Russia, USA), NIF (USA), EAST (China), and JT-60SA (Japan). The Federal Republic of Germany also has a globally unique facility in Wendelstein 7-X, currently the most powerful stellarator, and is ambitiously advancing the path toward a fusion power plant with a targeted action plan (High-Tech Agenda Germany).

In recent years, it has been demonstrated that the plasma conditions required for power plant operation can in principle be achieved experimentally. Consequently, issues related to materials development, systems engineering, and scaling are increasingly taking center stage. Although significant progress has already been made, major technical and economic challenges still need to be overcome before commercial use becomes possible.

• Extremely high temperatures and neutron fluxes: Materials must be protected from temperatures exceeding 100 million degrees and withstand intense neutron radiation without losing their mechanical integrity.
• Efficient tritium management: Since tritium is extremely rare on Earth and occurs only in trace amounts, it must be safely and efficiently produced, separated, processed, and stored on-site. The closed fuel cycle is a key prerequisite for economically viable fusion power plants.
• Reliable components: Durable, radiation-resistant materials for targets, walls, membranes, and electrical and optical systems are essential to achieve high availability and predictable maintenance cycles.
• Avoiding new dependencies: Critical raw materials must be used responsibly. Establishing reliable supply chains and long-term partnerships is important to avoid new geopolitical dependencies.
• Managing radioactivity: Strict regulatory requirements apply to the resulting low- and medium-level radioactive waste. Robust concepts for safety, disposal, and recycling are needed here.

With its various technology platforms, Fraunhofer IKTS can contribute to solving these challenges. In various development projects, IKTS has already demonstrated that ceramic materials and technologies hold great potential, particularly for commercial implementation. The institute offers itself as a partner for specific material-related and technological issues to enable accelerated implementation and establish future supply chains.

1. Nanoporous ceramic membranes for the fuel cycle and hollow spheres for tritium storage

The IKTS is developing ceramic membranes based on amorphous oxides, carbon, and zeolites that can be scaled up to industrial scale. In a promising project (FuelMem, BMFTR), Fraunhofer IKTS is developing and characterizing these membranes for the efficient separation and enrichment of gases—a crucial step toward tritium recovery and recycling in fusion reactors and thus toward a closed fuel cycle.

Another interesting area of development involves nanoporous hollow spheres made of various materials such as zeolite, carbon, or glass, which can be used for the storage of hydrogen and tritium as well as serving as target material.

Our in-house facilities for synthesis, characterization, and long-term testing enable us to bring innovative solutions directly to the application. Application testing can be conducted in close collaboration with partners such as KIT.

2. Enhanced first wall materials and transparent ceramics

The first wall of a fusion reactor is exposed to extreme thermal and mechanical stresses as well as intense radiation. To address this, IKTS develops ceramic materials such as Si-SiC and metal-ceramic composites (cermets), particularly those based on tungsten carbide (WC). These materials provide effective shielding against high-energy radiation. As a result, they could be suitable for various tokamak and stellarator components, particularly in the divertor region.

For optical diagnostic systems in fusion facilities, the IKTS develops transparent ceramics (e.g., spinel, MgO, Y₂O₃) that offer high mechanical, thermal, and chemical stability. They are suitable for use as lenses and protective windows at temperatures above 1500 °C and can be used up into the long-wavelength infrared range. The IKTS has its own production line for this purpose.

3. Stable Li-rich ceramics for the tritium breeding zone

Stable, custom-designed lithium ceramics are required for tritium production in the breeding zone. Here, the IKTS contributes its extensive experience in the development, manufacture, and characterization of Li-containing ceramics (e.g., LiAlO₂ and LATP) and ceramic spheres for various applications. This has already been successfully demonstrated for LiAlO₂ ceramics, which remain stable under the harsh conditions of molten carbonate fuel cells. The materials are characterized by high thermal stability (800 °C in reducing gas mixtures), adjustable specific surface areas, and production scalability (up to 25 kg per batch). This scalability is crucial for meeting the continuous material demand of future fusion power plants and establishing robust, reliable supply chains. The transferability of the processes to ceramics with higher lithium content, as well as adaptation to the specific requirements of fusion research, is assured.

The IKTS has a broad infrastructure, including grinding units, calcination furnaces, fluidized-bed granulation systems, diverse shaping technologies, and long-term testing facilities with various gases. Comprehensive analytical capabilities enable targeted development and quality control of the materials.

4. Infrastructure and expertise in handling radioactive materials

Working with radioactive substances such as tritium and activated materials requires special permits, laboratories, and qualified personnel. IKTS has facilities for the handling, analysis, engineering, and recycling of radionuclides. These include laboratories for the analysis of α-, β-, and γ-emitters, systems for the enrichment and separation of radioactive isotopes (e.g., tritium, C-14), as well as services for the conditioning and recycling of radioactive materials.

The institute holds a license to handle radioactive materials without restrictions regarding the type of radionuclides. A fully equipped nuclide laboratory enables chemical-technological work, damage analysis, and safe waste disposal within the scope of experimental operations and analysis.

5. Sensor technology and non-destructive testing for use in fusion reactors

The extreme operating conditions inside a fusion reactor place special demands on electrical and microelectronic components, for example in measurement, control, and regulation technology. Ceramic packaging technologies offer a promising solution for components exposed to ionizing radiation, extreme temperature fluctuations, or superheated steam. IKTS has many years of experience in the development and pilot production of sensor and microelectronic components based on HTCC and LTCC technology platforms. These components are already demonstrating their material-specific advantages in harsh environments such as nuclear reactors, gas turbines, and aerospace applications. The use of ceramic microsystems holds great potential in research reactors as well as future commercial systems, such as magnetic field sensors, fusion detectors, or high-frequency applications in diagnostics.

The IKTS is also working on robust electrically functional materials such as titanium oxides and spinels. These can be used in nuclear fusion technology for electrical control and energy transfer, for example as varistors to protect switching operations and for process control.

Modern non-destructive testing (NDT) methods ensure the quality and reliability of components for the overall fusion reactor system. Fraunhofer IKTS has more than 30 years of experience in the non-destructive testing of nuclear systems and facilities using ultrasound and acoustic emission. NDT systems contribute to ensuring overall safety, particularly in the commercialization of next-generation fusion power plants.
 

With these competencies, its modern infrastructure, and numerous reference projects, Fraunhofer IKTS makes an important contribution to solving the challenges of fusion research—from material development and tritium management to the safe handling of radioactive materials and the development of optical and electronic systems for extreme conditions. As a research and development service provider, Fraunhofer IKTS can thus support the transition from experimental fusion facilities to commercial power plant concepts.

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