V. A. Skuratov, R. A. Rymzhanov, A. E. Volkov, A. D. Ibraeva, N. S. Kirilkin, N. A. Medvedev, J. H. O’Connell, A. Janse van Vuuren, J. Neethling., M. V. Zdorovets were awarded the First JINR’s Prize for 2020 in nomination “Applied Physics Research” for their paper “Experimental study and multiscale modeling of latent tracks structure in radiation resistant dielectrics”.

The world shortage of an electrical energy and global climate changes are considered to be closely related to the wide use of traditional carbon-based energy production systems. This requires enforcing of the efforts on development and implementation of innovative nuclear power plants. Such a direction of further evolution of world power generation industry is advanced by the International Atomic Energy Agency (IAEA) [1]. The new IV generation of nuclear reactors developing within international projects and under regulation of IAEA have to provide higher standards of passive safety, efficiency of power generation and to bring the nuclear energetics to use of a stable withdrawn fuel cycle. In particular, new fast neutron nuclear reactors are supposed to utilize and recycle the nuclear waste, accumulated during decades of operation of power plants.

One of the main directions of the evolution of modern nuclear reactors is the development of new composite types of fuel, which imposed to demonstrate a high degree of stability against emergency situations. In this case, the required characteristics of the components are high thermal conductivity to reduce the core temperature of fuel cells, high radiation resistance, as well as inertness to the formation of radioactive isotopes during irradiation with neutrons generated during nucleus fission. Ceramic dielectric materials based on oxides and carbides possessing the indicated characteristics are considered as promising components (so-called inert matrices) of such a fuel.

The introduction of new types of materials for use in innovative reactors requires systematic studies of their radiation resistance, since during operation they are exposed to high particle fluxes (neutrons, alpha particles and fission fragments). It should be noted that the effect of fission fragments on the physical and mechanical properties of candidate materials for nuclear applications currently remains the least studied in comparison with other types of irradiations. This is partially due to the fact that such studies are possible only using high-energy heavy ion beams, accessible only at specialized facilities operating only in large world scientific centers, such as JINR and the Institute of Nuclear Physics of the Republic of Kazakhstan. The peculiarity of the interaction of high-energy heavy ions with solids is an extremely high level of target ionization in a narrow and extended region. This, on the one hand, forms promising application of heavy ion beams as a tool for nanoscale modification of materials and heterostructures. On the other hand, such features of the matter excitation create difficulties for the fundamental study of the processes occurring during the irradiation of solids with high-energy ions.

Present series of works delivers the investigation results of radiation resistance and changes in physical and mechanical properties in ceramic inert matrices. The studies were carried out by an international scientific group at the accelerators of the cyclotron complex of the Laboratory of Nuclear Reactions of JINR and DC-60 (Nur-Sultan, Kazakhstan), at the facilities of Nelson Mandela University (Port Elizabeth, South Africa). The theoretical description and modeling of the interaction of swift heavy ions with solids was carried out in the framework of international cooperation wiht the NRC “Kurchatov Institute”, the Lebedev Physical Institute and the Institute of Plasma Physics of the Czech Academy of Sciences (Prague, Czech Republic).

One of the striking results of the work, obtained using experimental and numerical methods, is the demonstration of the processes of recovery of the initial structure in damaged regions created by high-energy heavy ions in a separate class of radiation-stable materials (for example, aluminum oxide, magnesium oxide) [2]. Such recovery or recrystallization of the lattice significantly affects the radiation resistance of ceramic solids, especially at high radiation doses. Moreover, such processes can lead to a decrease in the number of defects in the already existing damaged structure [3]. The kinetics of damage formation and the morphology of structural changes in dielectrics under irradiation have been studied in a wide range of doses and temperatures, ion masses and energies [4, 5]. This makes it possible to predict long-term changes of the physical and mechanical properties of the target materials.

Investigations of the formation processes of defect structures on the surface of various dielectrics have shown significant differences in the damage kinetics in amorphizable and non- amorphizable materials [6]. It was found that the surface hillocks formed by irradiation can be crystalline and epitaxial with the initial crystalline surface, which suggests a recrystallization process initiated on the surface [7]. It should be noted that the most sensitive zone to irradiation is the near-surface region of solids, as well as the material-fuel interface region in multicomponent structures. Therefore, an experimental, analytical and numerical studies of the effects of swift heavy ions irradiation [8] on the structure and properties of the interface in composite materials are a necessary and urgent task of radiation materials science especially for applications in the field of nuclear energetics and electronics.

The new insights obtained in this work can be used for development of novel methods for the design of composite nuclear fuel and nanostructured electronic components, as well as for long-term prediction of the radiation resistance of promising materials for nuclear reactors.

1. Д. Донован, Ядерные реакторы следующего поколения: МАГАТЭ и МФП призывают к ускоренному внедрению соответствующих технологий, (2020).
2. R. A. Rymzhanov, N. A. Medvedev, J. H. O’Connell, A. Janse van Vuuren, V. A. Skuratov, A. E. Volkov, Recrystallization as the governing mechanism of ion track formation, Sci. Rep. 9 (2019) 3837.
3. R. A. Rymzhanov, N. A. Medvedev, A. E. Volkov, J. H. O’Connell, V. A. Skuratov, Overlap of swift heavy ion tracks in Al²O³, Nucl. Instruments Methods Phys. Res. Sect. B Beam Interact. with Mater. Atoms. 435 (2018) 121–125.
4. J. H. O’Connell, G. Aralbayeva, V. A. Skuratov, M. Saifulin, A. Janse Van Vuuren, A. Akilbekov, M. V. Zdorovets, Temperature dependence of swift heavy ion irradiation induced hillocks in TiO², Mater. Res. Express. 5 (2018) 055015.
5. A. Janse van Vuuren, M. M. Saifulin, V. A. Skuratov, J. H. O’Connell, G. Aralbayeva, A. Dauletbekova, M. V. Zdorovets, The influence of stopping power and temperature on latent track formation in YAP and YAG, Nucl. Instruments Methods Phys. Res. Sect. B Beam Interact. with Mater. Atoms. (2018).
6. R. A. Rymzhanov, J. H. O’Connell, A. Janse van Vuuren, V. A. Skuratov, N. A. Medvedev, A. E. Volkov, Insight into picosecond kinetics of insulator surface under ionizing radiation, J. Appl. Phys. 127 (2020) 015901.
7. J. H. O’Connell, V. A. Skuratov, A. Janse van Vuuren, M. Saifulin, A. Akilbekov, Near surface latent track morphology of SHI irradiated TiO², Phys. Status Solidi. 253 (2016) 2144–2149.
8. J. H. O’Connell, R. A. Rymzhanov, V. A. Skuratov, A. E. Volkov, N. S. Kirilkin, Latent tracks and associated strain in Al2O3 irradiated with swift heavy ions, Nucl. Instruments Methods Phys. Res. Sect. B Beam Interact. with Mater. Atoms. 374 (2016) 97–101.