After a thesis in atomic physics under the direction of Jacques Bauche (Université de Paris-Saclay) and Michel Busquet (CEA), I joined the CEA in 2001. I first developed a statistical version of the HULLAC code, describing the atomic states at the scale of electronic configurations rather than at that of levels, in order to have a more global modeling of hot plasmas. For this same purpose, we then developed with Christophe Blancard the OPAS opacity code, capable of including thousands of super-configurations to provide detailed spectra down to the spectroscopic scale of individual lines. Such data are particularly useful to the astrophysical community, with which we gladly collaborate, to model the radiative zone of the stars. We have also extended our approach to the non-Local Thermodynamic Equilibrium (and possibly unsteady) plasmas in order to build a radiative hydrodynamics post-processor: the SAPHyR code.