Advanced microstructural characterization of fusion materials: irradiation effects
Context: Design and construction of future reactors like ITER, MYRRHA and DEMO are extremely challenging projects with a huge impact on engineering and applied science development, industrial engagement and social perception of green energy to be extracted by efficient and safe nuclear operation. Development and qualification of structural materials for the future nuclear systems require demonstration of the tolerance of mechanical properties to neutron irradiation to satisfy acceptable safety limits. Therefore, the industrial engineering effort to produce new materials with dedicated microstructure and chemistry to resist impact of the neutron irradiation damage is ongoing. One of the major milestones on the European Fusion Roadmap towards DEMO is the preparation of ITER for nuclear phase of operation, where thanks to D-T reaction fusion power must be generated in large excess compared to the inlet power needed to heat-up the plasma.
State of art: In ITER as such, the so-called in-vessel components will be a subject of high flux of energetic neutrons, originating from the fusion reaction, which will cause degradation of physic-thermo-mechanical properties of the first wall components. Proper evaluation of the operational lifetime of these components and reliable prediction of the irradiation damage accumulation is important for the definition of the resources required to run ITER. At the same time, understanding of the physical phenomena involved in the degradation of plasma-facing components (PFC) is rather challenging due to the interplay of several mechanisms involving mechanical stresses, thermal gradients and superimposed neutron irradiation. Among different PFCs, divertor is the one which is subject to most severe operational conditions.
Research hypothesis: To advance our knowledge of PFC under irradiation, this PhD project covers an advanced microstructural study of the main materials constituting ITER in-vessel components (i.e divertor and test blanket module). The project aims to rationalize the degradation of thermo-mechanical properties of tungsten (W), steel and copper alloys by revealing the microstructural changes induced after the fusion-relevant irradiation conditions. The microstructural information will be obtained by transmission electron microscopy (TEM) and advanced TEM tools to perform in-situ studies where simultaneous TEM observations and thermal/mechanical load on the pre-irradiated material will be exposed. The materials that will be investigated in this PhD project are being the main EU candidates for the application in ITER and DEMO, and the irradiation conditions applied are relevant to those as expected in ITER and DEMO. The research samples are the miniaturized bending, tensile, fracture toughness specimens, which were irradiated in the course of programmes held at BR2 in 2017-2020. The mechanical data for these samples is available. The materials to be investigated are listed in this publications: https://doi.org/10.1016/j.jnucmat.2021.153009; https://doi.org/10.1016/j.ijrmhm.2020.105437; https://doi.org/10.1016/j.ijrmhm.2018.04.003
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Co-mentorVan Renterghem Wouter
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