[en] Full text of publication follows: Nuclear energy contributes to most than 75% of the French electricity thanks to the operation of 58 generation 2 reactors located on 19 sites built from the 70's to the end of the 90's. France also developed for a long time a fully integrated nuclear industry covering the whole nuclear fuel cycle, from the ore mining to the fabrication of the fuel for the front-end, from the reprocessing up to the MOX fuel fabrication and storage facility and in the near-future geological repository for the back-end. This investment allows France to produce a low-carbon electricity with the second lowest GHG emissions intensity, in the range of 90 g CO₂/KWh. Such a very beneficial figure is directly related to the high contribution of nuclear in the electricity mix combined with renewables energies, in particular hydro. Greenhouse gases emissions are very relevant to assess the respective influence on the global climate change, but they do not address the whole potential environmental impact of any activity. However, such a question is crucial for assessing the respective sustainability of such an activity, in particular nuclear energy which is thought to be very detrimental by a large part of the public opinion. In order to address this question, we developed a dedicated life cycle assessment (LCA) tools referred to as NELCAS, the specificity of which is to focus on the first order parameters and avoiding any 'black-box' effect which can exist in commercial LCA tool. Thanks to the recent transparency and nuclear safety law (2006), in- and out- fluxes of matter and energy for any of the fuel cycle facilities are now publicly available. We hence used this significant set of measured data to feed our model and assess the most usual environmental indicators such as land use, different types of atmospheric emissions (GHG, SOx, NOx, particles...) and aqueous release (chemical effluents, eutrophication potential,...)... We also specifically quantify the specific indicators for nuclear activities, i.e. radioactive aqueous and atmospheric release and nuclear waste. We consider the whole fuel cycle as well as the contribution of the whole lifetime of any plant, from cradle to grave (construction, operation, dismantling). We were hence able to quantify what is the actual and current environmental impact of nuclear energy on a very large set of environmental indicators, and compare it to already published data for other energy sources. This demonstrates the very beneficial impact of nuclear energy to the overall environmental preservation beyond the well-known CO₂ emissions, and allows to specifically evidence the positive influence of the recycling operations. (authors)