[en] This thesis is devoted to the simulation of incompressible or low Mach turbulent flows, for nuclear safety applications. In particular, we focus on the development and analysis of performing numerical schemes for the Large Eddy Simulation technique. These schemes are based on fractional step methods of pressure correction type and on nonconforming low degree finite elements. Two requirements seems essential to build such schemes, namely a control of kinetic energy and the accuracy for convection dominated flows. Concerning the time marching algorithm, we propose a Crank-Nicolson like scheme for which we prove a kinetic energy control. This scheme has the advantage to be numerically low dissipative (numerical dissipation residual is second order in time). Concerning the low accuracy of the Rannacher-Turek discretization, two approaches are investigated in this work. The first one consists in building a penalized scheme constraining the velocity degrees of freedom tangent to the faces to be written as a linear combination of the normal ones. The second approach relies on the enrichment of the pressure approximation discrete space. Finally, various numerical tests are presented in both two and three dimensions and for general meshes, to illustrate the capacity of the schemes and compare theoretical and experimental results. (author)

[en] Thesis presentations have been organised in sessions which respectively addressed issues related to radiation safety, and to environment and health (urban atmosphere, dry deposition of aerosols, therapeutic benefit of an injection of mesenchymal stem cells, colorectal lesions, role of toll-like receptors (or TLR) in immune orientations induced by an abdominal irradiation. Plenary sessions also addressed these issues. Then sessions addressed issues related to parallel effects in low doses, to the parallel modelling of materials, to containment and aerosols, to neutron spectrometry and dosimetry. Some parallel sessions addressed issues related to geosphere, to severe accidents and fires. A plenary session addressed the Fukushima accident, the related R and D, and future investment. Poster sessions addressed several topics: safety (fire, containment, neutronics, civil engineering, methods), and radiation protection (radionuclide metrology, toxicology, radio-biology, dosimetry).