PhD Defense | Koray Iroc | Advanced microstructural characterization of fusion materials: irradiation effects

Advanced microstructural characterization of fusion materials: irradiation effects

Nuclear fusion is regarded as a promising long-term solution for meeting the rising global energy demand, while offering a potential for abundant, intrinsically safe and low-carbon emission electricity. However, achieving fusion energy on industrial scale requires overcoming several critical engineering and scientific challenges, including development of radiation-resistant plasma-facing component (PFC) materials to withstand fusion conditions. Tungsten (W) has emerged as the leading candidate for divertor and first-wall components in next generation fusion reactors due to its exceptional thermal properties. Nevertheless, under fusion-relevant operational conditions, PFCs undergo significant microstructural degradation, including defect formation, accumulation and transmutation-induced precipitation, all of which impact the mechanical stability and eventually lifetime of the component. A comprehensive understanding of these irradiation-driven mechanisms is essential to design, simulate and optimize durable fusion materials.

Transmission electron microscopy (TEM) is a powerful technique to visualize the microstructure of the inspected material. For nuclear science, it enables to reveal microscopic features, their characteristics and morphologies, induced by irradiation. Furthermore, combining with in-situ heating enables information about high-temperature stability of the radiation-induced defects. Despite extensive research efforts, critical gaps remain in literature regarding the microstructural evolution of PFCs under different irradiation conditions. The response of the material strongly depends on irradiation type (neutron, ion, plasma etc.), dose (dpa), temperature, initial microstructural state and alloy composition, yet systematic comparisons across irradiation conditions are limited. This thesis aims to address some of these gaps by developing a comprehensive dataset describing the defect evolution of PFCs under both neutron and heavy-ion irradiation across a range of irradiation parameters. The work focuses on the experimental investigation of the fundamental microstructural mechanisms such as defect formation, aggregation and recovery as well as understanding radiation-induced hardening and the role of transmutation products.

Promoter:

• Joke Hadermann (UANTWERPEN)

SCK CEN mentors:

• Dmitry Terentyev
• Wouter Van Renterghem