Wall Forum 2026

Key to the accelerated deployment of advanced reactors is rapid qualification of core materials. The lack of test reactor availability, the extensive irradiation time required, and the resulting high cost make traditional routes to obtain the data needed to qualify core materials impractical in the near term. Ion irradiation coupled with advanced, rapid characterization constitute a solution to this dilemma. Using one ferritic-martensitic alloy and one austenitic alloy, we show that the key microstructure and mechanical properties created in reactor can be replicated with ion irradiation. Computational materials modeling is used to inform the ion irradiation parameters and to provide predictive capability of material properties. Results from this methodology are benchmarked against reactor data on the same alloy, and codified in ASTM standards, thus providing licensees with a justification of the efficacy of their core material performance when establishing their safety case for the regulator. [mehr]

Structural materials in nuclear environments are often subject to simultaneous combinations of irradiation flux, elevated temperature, and mechanical load. In addition, environments in-service are likely to be inhomogeneous with respect to both position (spatial variation) and time (temporal variation). Despite knowledge of this superposition and heterogeneity, the performance of structural materials is commonly assessed through sequential single effects tests, which may not accurately represent the conditions experienced in operando. At the University of Wisconsin (UW) Ion Beam Laboratory (IBL) we are developing an in situ ion irradiation mechanical testing (I3MT) facility to subject small scale specimens to mechanical loading (up to 2.5 kN), and elevated temperatures (up to 800°C), during ion irradiation (3 MeV H+). In contrast to previous irradiation creep facilities, this facility will also allow for periodic loads to be applied, enabling tensile testing and irradiation fatigue to be studied. Independently-controlled grip heaters enable the generation of temperature gradients along the gauge length of specimens, enabling heterogeneous sample environments to be established. This allows for investigation of the effect of temperature on radiation damage evolution and emulation of in-service conditions such as fuel cladding or fusion divertor components. This facility will significantly accelerate the evaluation of microstructural evolution under multiple stimuli, advancing the understanding of irradiation-induced degradation mechanisms, and thus development of better materials to withstand coupled nuclear extremes. [mehr]

Advanced structural and functional materials are needed to enable future fusion concepts ranging from governmental programmes to private initiatives. Currently, only few materials and manufacturing solutions hold promise to accelerate the fusion vision. Here, the overarching irradiation damage and applicability challenges with fusion structural steels will be discussed with a view towards potential path forward. Ongoing efforts at the University of Birmingham on Vanadium alloys R&D as potential blanket and heat sink materials will be discussed with its comparison made with RAFM/ODS steels, especially for liquid Li systems. Finally, some ongoing R&D on dissimilar metal joining, near-net shape manufacturing and their overarching irradiation damage scenarios will be discussed. [mehr]

Auf dem Weg zu einem Fusionskraftwerk befindet sich die Forschung an einem wichtigen Übergang von Grundlagenexperimenten mit wenigen Sekunden Betriebszeit hin zu Kraftwerksanlagen mit Dauerbetrieb. In diesen Anlagen wird die Fusionsreaktion enorme Wärmeleistung und Strahlung erzeugen. Die Entwicklung von Hochleistungskomponenten, die diesen Bedingungen widerstehen können, ist deshalb essentiell. Im Hochwärmeflussteststand GLADIS ist es möglich, Materialien und Komponenten der erwartenden hohen Belastung auszusetzen. Ein hochenergetischer Teilchenstrahl erzeugt Wärmelasten von bis zu 45 MW/m². Im Moment ist die Belastungsdauer dabei auf maximal 45 s begrenzt soll aber im Rahmen des Projektes GLADIS HD auf ≥ 30 Minuten erhöht werden. Dafür ist ein Ausbau des Gesamtsystems inklusive Energie- und Kühlsystem sowie Steuerung und Diagnostik nötig. Durch die erweiterten Kapazitäten wird es möglich auch Effekte, mit längeren Zeitkonstanten, wie z. B. thermisches Kriechen, wissenschaftlich zu evaluieren. So können Materialien und Komponenten unter realistischen Bedingungen getestet und für den Einsatz in einen Fusionskraftwerk qualifiziert werden. Als hochrelevanter Anwendungsfall werden neue auf Wolfram basierende Wandelemente für den Einsatz im Stellarator W7-X qualifiziert. Damit wird ein wichtiger Beitrag für den ersten Betrieb eines Stellarators mit einem kraftwerksrelevanten Wandmaterial geleistet. GLADIS wird durch den Ausbau seine Stellung als eine der wichtigsten Einrichtungen für Hochwärmeflusstests in Europa weiter festigen können und die Verfügbarkeit dieser wichtigen Testkapazitäten für den Forschungsstandort Deutschland wird gesichert. Dieser Vortrag gibt eine Übersicht über das Gesamtprojekt inklusive einer detaillierten Beschreibung der einzelnen Schritte. Ein besonderer Fokus liegt dabei auf den Schnittstellen innerhalb des IPPs die essentiell für eine erfolgreiche Umsetzung sind. [mehr]

Understanding the mechanisms governing tritium retention in structural materials, such as EUROFER97, is essential for ensuring both safety and tritium self-sufficiency in future fusion reactors. In this work, EURORFER97 samples were exposed either to a low energy electron-cyclotron-resonance deuterium (D) plasma or to D₂ gas at various temperatures. Clear differences emerged between plasma and gas exposures: plasma loading resulted in a single dominant low-temperature desorption peak, whereas gas loading resulted in additional peaks at higher temperatures. These experimental results were simulated using a state-of-the-art reaction-diffusion code (TESSIM-X) to derived de-trapping energies and trapping barriers. The results indicate the presence of traps with high-energy barrier for entering the trap, whose occupation strongly depends on the solute D concentration. These findings provide new insight into D behavior in reduced activation ferritic/martensitic (RAFM) steels, with direct implications for tritium retention in reactor environments. [mehr]

Plasma–material interaction (PMI) is one of the major challenges in the development of future fusion reactors, as it critically affects plasma–facing components and, in particular, the performance of diagnostic first mirrors. This work investigates PMI phenomena relevant for the cleaning of diagnostic first mirrors in fusion reactors. Representative rhodium mirrors have been produced and contaminated with boron and boron–tungsten deposits, to resemble redeposition phenomena occurring during operation, and exposed to deuterium and argon plasmas in the GyM linear device at ISTP, in Milan. The outcome of the study showed that deuterium plasmas effectively removed boron nanoparticles with minimal mirror damage, while argon plasmas were most effective for tungsten removal and induced surface nanostructuring. The study demonstrates the complementarity of argon and deuterium plasmas for cleaning purposes and establishes a laboratory-scale framework to assess erosion and cleaning efficiency, providing insights for optimizing in-situ mirror cleaning in ITER and future fusion devices. [mehr]

The Electron Cyclotron Resonance Heating system for the Divertor Tokamak Test (DTT) relies on a series of mirrors to inject high-frequency millimetre waves into the reactor vessel. The last launching mirrors transmit microwaves directly into the plasma while withstanding extreme conditions in the tokamak ports. Significant challenges include magnetic torques that could affect steering, intense heat loads, and flux of energetic neutrals. Developing mirrors that withstand this environment and remain effective in microwave reflection, without increasing roughness-related ohmic losses, is crucial. A current investigation involves combining a dielectric ceramic substrate with tungsten coatings to optimize performance and lifetime. In this project, three types of tungsten multilayers were deposited on ceramic substrates with radio-frequency magnetron sputtering. The coatings were analysed in their morphology, composition, adhesion, and electrical resistivity, and exposed to fusion-relevant plasmas in a linear device. Results indicated good adhesion and maintenance of the coating’s morphology post-exposure. Comparison with an established model suggested an erosion enhancement mechanism, and preliminary SRIM-2013 simulations explored the impact of impurities on sputtering. Additionally, a first estimation of ohmic losses provided insight into their magnitude. The project represents the first experimental study on this innovative approach, and the extensive characterization provided a solid assessment of the coating production effectiveness and of the coating's main properties. [mehr]