Scientists from the National Research Nuclear University MEPhI have clarified how changing the nanostructure of materials for future energy fusion reactors influences their plasticity, heat resistance, and other important properties.

Developing new fast-neutron reactors and an efficient fusion reactor is one of the most promising nuclear power engineering projects. The former will make it possible to close the nuclear fuel cycle and make the nuclear power industry more environment-friendly. The latter will enable the creation of a fundamentally new method of energy production. The most well-known project designed to expedite the emergence of energy-producing fusion reactors is the International Thermonuclear Experimental Reactor (ITER).

It is difficult to create new energy devices because all of them involve extreme conditions in the zone of energy production. This is why some incredibly high requirements are made on materials to be used in the active zone of new reactors. Exposed to high temperatures and streams of high-energy radiation, existing materials tend to degrade quickly. The most durable of these can sustain radiation doses, where each atom in the matter is displaced between 80 and 90 times. This parameter should be twice as large for thermonuclear energy installations. It is materials’ stress resistance in the energy production zone that determines whether a reactor can be considered efficient and safe.

MEPhI researchers intend to deal with this problem with the help of nanotechnologies. Ferrite-martensite steels on the basis of Fe-Cr alloys and oxide dispersion-strengthened steels are regarded as the most promising materials for future energy installations. The MEPhI researchers demonstrated experimentally how these materials could be restructured at the atomic level and how atoms were redistributed, leading to a substantial rise in fragility and loss of plasticity. The research was published in Journal of Nuclear Materials and Journal of Nuclear Materials and Energy.

It is established that changing the nanostructure can change the properties of a construction material and as a consequence significantly reduce the lifecycle of active zones. In some cases, however, scientists manage to select nanostructure changes that considerably expand opportunities for using materials and provide them with unique properties, such as high heat resistance.

During the experiments, Fe-Cr model alloys and oxide dispersion-strengthened (ODS) steels were exposed to various impacts, whereupon the emergent nanoscale changes in properties were recorded with the help of atom probe tomography.

"Our work was to analyze the nanoscale state of the materials and its restructuring under various impacts. We induced thermal ageing and used beams of metal ions to establish that their influence could lead to the breakage of nanostructure," Sergei Rogozhkin, deputy head of the Department of Extreme States of Matter Physics at the MEPHi Institute of Nuclear Physics and Technologies, told RIA Novosti.

According to Mr. Rogozhkin, their research could be used to create materials for ITER and for future energy installations. "ITER is meant to demonstrate the efficiency of the thermonuclear reactor concept. Requirements on materials are high at this stage, but a next-generation thermonuclear installation will create even more extreme conditions and fundamentally new materials, including those we are studying now, are being developed precisely for them," he explained.