3 minute read
Atomistic modelling of materials
Using a broad range of atomistic modelling techniques, researchers in the Nuclear Materials Modelling and Characterisation group, design materials for nuclear energy production at the atomic scale, and investigate the fundamental structure and properties of nuclear materials.
Atomic scale simulation is a powerful tool. Some of the main advantages of computer simulation over direct experimentation in nuclear materials research are cost, accessibility to properties that are experimentally difficult to determine and safety.
Molecular dynamics is used to simulate the generation of defects and recovery of radiation damage in materials, a key consideration in the selection of nuclear materials. Dynamic processes typically happen on the picosecond (one trillionth of a second) time scale. Direct observation of these ultra-fast processes is difficult experimentally, but can be captured in computer simulations.
By manipulating the composition and microstructure of materials in order to control the behaviour of defects induced by radiation, modelling can predict material performance on the macro- and engineering-level. Comparison of predictions with experimental observations can provide validation of the computer models, and increase confidence in predictions of the material’s performance. Atomicscale design is currently used to speed up the improvement of existing materials, but, in the longer term, it aims to conceive revolutionary new materials that do not arise through gradual design modifications.
Researchers in the Nuclear Materials Modelling and Characterisation group propose and test new materials that might be capable of accommodating the products of element transmutation and crystal damage that are natural consequences of the radiation processes. New materials are potentially useful as structural nuclear reactor materials, additives to nuclear reactor fuel or waste-forms.
Using ab initio density functional theory and empirical atomic simulation methods, researchers simulate the expected radiation tolerance, response to displacement caused by irradiation and stability under transmutation, in a variety of ceramic materials.
The results of the simulations provide researchers with an indication of the ceramic recipes that might form stable products during nuclear decay.
Theoretical materials are then manufactured and their properties tested in real life by scientists at ANSTO.
The Nuclear Materials Modelling and Characterisation researchers examine material properties before, during and after radiation damage processes. The effects of radiation damage on the thermal and mechanical properties of nuclear materials are key concerns in the nuclear industry.
One area of active research is the effect of radiation damage and additives on the thermal conductivity of nuclear materials such as uranium dioxide (UO2).
When chromium oxide is added to a UO2 fuel pellet, it reacts with the radioactive decay product plutonium (Pu), and forms PuCrO3. The poorer thermal conductivity can explain the increase in fractures and grain structure seen in a UO2 fuel pellet when chromium and aluminum oxides are added.
The simulations provide information to support the development of new materials that could be used in advanced energy applications such as advanced fission and fusion systems, as well as specialist materials for the high technology sector.
Pictured
ANSTO’s Dr Meng Jun Qin, viewing a radiation damage process in the ceramic Y2TiO5 at the atomic scale using molecular dynamics simulations.
Contact
mengjun.qin@ansto.gov.au
COLLABORATORS
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ANSTO
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Westinghouse Electric Sweden
RESEARCH FACILITY / TECHNIQUE
Nuclear fuel cycle research Nuclear materials research
ANSTO scientific computing
Molecular dynamics simulations (LAMMPS, DL_POLY) Density functional theory (VASP, CASTEP, DMOL3) RESEARCHER TEAM
Dr Eugenia GUO Dr Greg LUMPKIN Dr Simon MIDDLEBURGH
Dr Meng Jun QIN
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1
2
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PUBLICATIONS
Journal of Physics: Condensed Matter 2014
Solid State Ionics 2013
Journal of Materials Chemistry 2013 Journal of Physics: Condensed Matter 2013
Journal of Materials 2013
Journal of American Ceramics Society 2013
Journal of Nuclear Materials 2013 Modelling and Simulation in Materials Science and Engineering 2017
