A postdoctoral position is available at CEA near Paris, France.

The candidate will use electronic structure calculations to compute the xenon diffusion coefficient in uranium dioxide UO2, which is the standard nuclear fuel used in pressurized water nuclear reactors. During in-pile operations, the fission of uranium yields a wide variety of fission products (including xenon) that generates numerous point defects while slowing down in the material. This in turn governs the evolution of the fuel physical properties under irradiation. In this study we are interested in calculating the xenon diffusion coefficient in order to better understand the release mechanisms. Results will be assessed against experimental data and used as input data in higher scale models of xenon diffusion in UO2.

This project will be carried out in close collaboration with other laboratories at CEA for experimental measurements of diffusion coefficients, as well as with the Los Alamos National Laboratory, USA, for the higher scale models of xenon diffusion in UO2.

The ab initio calculation of diffusion coefficients has never been achieved before in actinide compounds because the relevant computational tools were either not available or not adapted. The candidate will, however, benefit from the latest developments of the electronic structure code abinit, partly developed at CEA, which allow such calculations to be done in the framework of density functional perturbation theory (DFPT).

The candidate will need to possess a solid background in density functional theory (DFT). Knowledge of general thermo-chemistry and solid-state physics (in particular phonons in materials) will also be appreciated.

Please send applications to boris . dorado @ cea. fr. It should include a CV, a motivation letter, and two recommendation letters.

This project is the continuation of the following studies:

• B. Dorado et al., DFT+U calculations of the ground state and metastable states of uranium dioxide, Phys. Rev. B 79, 235125 (2009)
• B. Dorado, P. Garcia et al., First-principles calculation and experimental study of oxygen diffusion in uranium dioxide, Phys. Rev. B 83, 035126 (2011)
• D. A. Andersson et al., U and Xe transport in UO2+-x: Density functional theory calculations, Phys. Rev. B 84, 054105 (2011)
• B. Dorado, D. A. Andersson, C. R. Stanek, B. P. Uberuaga, P. Garcia, et al., First-principles calculations of uranium diffusion in uranium dioxide, Phys. Rev. B 86, 035110 (2012)
• D. A. Andersson, P. Garcia, B. Dorado, B. P. Uberuaga, C. R. Stanek et al., Atomistic modeling of intrinsic and radiation-enhanced fission gas (Xe) diffusion in UO2+-x: Implications for nuclear fuel performance modeling, J. Nucl. Mater. 451, 225 (2014)