# Heat transport in novel nuclear fuels

**Project reference: **2213

As the costs of electricity in Europe are rapidly growing, peaking more than 600 EUR per MWh in the end of 2021 and having a 200 EUR per MWh on regular basis, a stable and reliable as well as steady delivering energy source is required. This cannot be easily achieved from renewable energy sources due to their rather low efficiency and not solid reliability. Such requirements can be more easily achieved from the nuclear energy, provided some improvements to nuclear fuels are applied. There is a large potential of usage of the so-called Th-cycle with waste to be secured only in matters of years, maximum of a decade, as a large advantage over existing MOX, or UO_{2} based fuels that are currently applied. Another advantage is to used fuels that are capable of operating at higher temperature, i.e. with higher efficiency of the heat transfer. Naturally, metallic ones will overcome insulating oxides and therefore the actinide compounds will be of our interest. In this project we would like to simulate the thermal expansion (safety feature) as well as heat transfer, both quantities related to the lattice dynamics. To understand the limits of the fundamental contributions to the heat transfer in novel, potential nuclear fuels for the generation IV reactors, the large quantum-mechanical calculations can be performed on the largest czech national HPC infrastructure.

**Project Mentor:** Dominik Legut

**Project Co-mentor: **Dr. Urszula D. Wdowik

**Site Co-ordinator: **Karina Pešatová

**Learning Outcomes:
**Knowledge how to calculate dynamical properties of solids, obtain phonon-dependent thermodynamical quantities, simulate transport phenomena in solids.

**Student Prerequisites (compulsory):
**unix commands, bash, editors vim or emacs, crystal structures and general knowledge of the solid state physics, see the training material

**Student Prerequisites (desirable):
**Knowledge of sed, awk, and regular expressions which can simplify partially the postprocessing. The knowledge of python and programming in general will be very large advantage for post-processing and development.

**Training Materials:
**

- https://www.geeksforgeeks.org/essential-linuxunix-commands/
- – KITTEL, Charles. Úvod do fyziky pevných látek. Praha: Academia, 1985, ISBN-13: 978-0471874744.
- – MANES, L. Actinides – Chemistry and Physical Properties. Berlin, Heidelberg: Springer-Verlag, 1985 ISBN 9783540390428.
- – MARTIN, R. M., Electronic Structure: Basic Theory and Practical Methods, Cambridge University Press, 2004, ISBN-13: 978-0521782852.
- – ASCROFT N. W. and N. D. Mermin, Solid State Physics, Cengage Learning, 1976, ISBN-13: 978-0030839931.
- – KAXIRAS, Efthimios. Atomic and electronic structure of solids. New York: Cambridge University Press, 2003. ISBN 978-0521523394.
- – CHAIKIN, P. M. and T. C. LUBENSKY. Principles of condensed matter physics. Cam- bridge [u.a.]: Cambridge Univ. Press, 2007. ISBN 9780521794503.
- SINGLETON, J., Band Theory and Electronic Properties of Solids, Oxford Master Series in Physics, 2001, ISBN-10: 0198505914.
- – BLUNDELL, Stephen. Magnetism in condensed matter. Oxford: Oxford University Press, Oxford master series in condensed matter physics. ISBN 9780198505914.
- – GRIMVALL, Göran. Thermophysical properties of materials. Enl. and rev. ed. New York: Elsevier, 1999. ISBN 0444827943.

**Workplan:
**

1w: Introduction to the density funcitional theory calculations.

2w: Performing electronic structure calculations.

3w: Introduction to the calculations of lattice dynamics (phonons).

4w: Analysis of the calculated results – physical quantities to acquire.

5-8w: Performing calculations of phonon-phonon interaction for simple systems.

**Final Product Description:
**Determination of the leading terms in thermal conductivity for given materials. Finding the limits of the models.

**Adapting the Project: Increasing the Difficulty:
**To increase complexity of modelling we can involve calculations of electron-phonon interactions.

**Adapting the Project: Decreasing the Difficulty:
**Omission of the electron-phonon interactions (QuantumEspresso, EPW codes). Application of standard routines of the Phono3py code and limitation of calculations to lattice thermal conductivity.

**Resources:
**Phonopy, Phono3py, VASP, Quantum Espresso, EPW, all codes are available at IT4Innovations HPC clusters within the supervisor’s group

**Organisation:
**IT4Innovations National Supercomputing Center at VSB – Technical University of Ostrava

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