The sustainability of nuclear fission energy will be ensured when Generation IV (GenIV) systems are deployed. Thermo-nuclear fusion represents in the longer term a virtually inexhaustible source of energy, with potentially very high standards of sustainability, efficiency and safety. Despite differences between GenIV fission and fusion reactors, in both technologies materials will be exposed to high levels of irradiation and high temperatures, in contact with potentially aggressive non-aqueous coolants. Thus, several materials issues are common.
In this context, the M4F project (Multiscale modelling for fusion and fission materials) promotes cross-fertilization between the nuclear fission and fusion materials modelling and characterization communities, to work on structural materials that are of interest for both, namely ferritic/martensitic (F/M) steels. These offer excellent radiation-induced swelling resistance and thermal properties, as compared to austenitic steels, but suffer from low temperature neutron irradiation hardening, embrittlement and loss of uniform elongation, with impact on design rules and codification activities.
Specifically, two are the overarching objectives of the M4F project:
O-a) Develop physical understanding and predictive models of the origin of localised deformation under irradiation in F/M steels and its consequences on the mechanical behaviour of components, starting from modelling and understanding the changes caused by irradiation on the microstructure and microchemistry of the materials involved;
O-b) Develop a methodology to use ion irradiation as a tool to evaluate radiation effects on materials, minimising artefacts with respect to neutron irradiation experiments and allowing evaluation of not only microstructural change, but also mechanical property changes, via nanoindentation, applying it to F/M steels.
The complexity of the processes that drive the production and evolution of microstructural damage induced by neutron irradiation and the consequences it has on the material’s behaviour require large R&D efforts, that advise synergies to be exploited and collaboration to be promoted between fusion and fission materials research groups, applying a multidisciplinary approach. In it, both modelling and experiments at different scales are integrated to enable the understanding of the complex phenomena associated with irradiation damage in F/M steels, providing input to design codes.
