Cs diffusion mechanisms in UO investigated by SIMS, TEM, and atomistic simulations.

Experimental investigations and atomistic simulations are combined to study the cesium diffusion processes at high temperature in UO. After Cs implantation in UO samples, diffusion coefficients are determined using the depth profile evolution after annealing as measured by secondary ion mass spectrometry. An activation energy of 1.

Improved SMTB-Q model applied to oxygen migration and pressure phase transitions in UO.

The second-moment tight-binding variable-charge (SMTB-Q) interatomic potentials have been implemented in the molecular dynamics (MD) code LAMMPS in order to study the static and dynamical properties of uranium dioxide UO. With respect to a previous work on UO the SMTB-Q model has been slightly modified in introducing a splitting energy of the U 5f  orbitals. This improvement results in a better description of the electronic structure of UO namely the gap estimation which is now close to the experimental value (~2 eV).

Effect of the Oxygen Potential on the Mo Migration and Speciation in UO and UO.

Molybdenum is an abundant element produced by fission in the nuclear fuel UO in a pressurized water reactor. Although its radiotoxicity is low, this element has a key role on the fuel oxidation and other fission products migration, in particular in the case of an accidental scenario. This study aims to characterize the behavior of molybdenum in uranium dioxide as a function of environmental conditions (oxygen partial pressure, high temperature, UO oxidation) typical of an accidental scenario.

A novel method for calculating the energy barriers for carbon diffusion in ferrite under heterogeneous stress.

A novel method for accurate and efficient evaluation of the change in energy barriers for carbon diffusion in ferrite under heterogeneous stress is introduced. This method, called Linear Combination of Stress States, is based on the knowledge of the effects of simple stresses (uniaxial or shear) on these diffusion barriers. Then, it is assumed that the change in energy barriers under a complex stress can be expressed as a linear combination of these already known simple stress effects.