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Overview
The FEMaS-CA will create a European research environment in which a consistent study and characterization of the key materials for fusion power generation will be possible to an optimum extent.
In agreement with EFDA, the key materials which have been identified as most relevant ones for the CA activities are:
- ODS steels
These are 9-14% Cr steels of low activation composition which are reinforced with finely dispersed oxide nano-particulates. ODS steels may provide high strength and creep resistance at temperatures 200°C higher than the baseline EUROFER grades (i.e. 750°C operation temperature compared to 550°C operation temperature for EUROFER).
Critical items which require sophisticated characterization methods are the distribution of particles in the matrix, the consequences of severe plastic deformation and heat treatment on the matrix evolution and the matrix/particle relationship, and the effect of irradiation damage on the matrix plasticity at low temperatures. - W-based materials
Tungsten-based materials are foreseen for the use as plasma-facing materials. Problems associated with presently available tungsten grades are the narrow temperature window between irradiationem brittlement at lower temperatures and grain growth and the resulting loss of mechanical properties at high temperatures.
With present grades in irradiated condition, this window is between ca. 900°C and 1100°C whereas 650°C to 1300°C would be required for fusion reactor operation. EFDA is supporting development efforts to improve tungsten-based materials accordingly.
This development requires the intense use of characterization methods in a way as described above for the ODS steels. - Functional coatings
Functional coatings have to be deposited with a tailored composition and with crystalline nanostructure to provide the required barrier, isolation and/or corrosion protection function. This structure has to be stable under intense neutron irradiation, so that no migration channels for atomic species can form.
The characterization methods of this project will allow studying the surface and bulking processes taking place under operation conditions (chemistry, formation of trapping sites, etc.). This knowledge is needed for the development of effective and irradiation-stable coatings.Emphasis will also be laid on the modelling of irradiation damage within this project.
The development of these materials towards high irradiation dose tolerance requires a fundamental understanding of the specific damage processes taking place under irradiation with a fusion relevant neutron spectrum.
At present no irradiation facility is available which reproducs the fusion neutron energy spectrum of a reactor with sufficiently high doses. Thus, on the experimental side irradiations are being carried out in fission reactors with less energetic neutron spectra and with energetic ion beams.
The need for a basic understanding of fusion irradiation damage and the lack of an exact experimental irradiation and verification method has triggered an intense activity in the field of irradiation damage modelling. The methods applied within the frame of the EFDA modelling programme span from ab initio work to the mesoscopic level of dislocation movement.
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FEMaS - CA The research leading to these results has received funding from the European Atomic Energy Community’s Seventh Framework Programme (FP7 / 2007-2011) under Grant Agreement No 224752. |
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| © 2009-2011 Max-Plack-Institut für Plasmaphysik (Garching, Germany) |