Overall assessment of the environmental footprint of nuclear energy as a function of future fuel cycle options
Résumé
For the first time in his history, Humankind has to face a worldwide and global crisis, i.e. the climate change which could lead to major modifications of our environment. Although it may not be the sole reason, anthropic activities are at least partially responsible for such a rapid evolution due to the release of Green-House Gases (GHG) in the atmosphere, most of them coming from the fossil energies combustion. Despite its very beneficial low GHG emissions, nuclear energy is severely questioned by the public opinion about its anticipated detrimental environmental effect, in particular due to nuclear accident such as Fukushima, or the accumulation of long-lived nuclear waste. Furthermore, the complexity of nuclear energy prevents anybody to easily get an overall assessment of its environmental footprint. However, nuclear energy which has the potential to contribute to mitigate the climate change, will only develop if it succeeds to be transparent about its potential impact and risk, and to involve society and citizens in any long-term decision.In such a context, developing objective and quantitative set of environmental indicators for nuclear energy is a challenging but mandatory step to support the development of unbiased assessment of the actual risk and benefit from nuclear energy. The difficulty of such a task lies in gathering relevant and reliable datasets for a very large number of facilities which can be dispersed worldwide. Hopefully, France developed since the early 70's a complete and consistent nuclear energy system which allows France to produce more than 75 percent of its electricity thanks to 58 nuclear reactors. Furthermore, the strict French regulations oblige the different operators to yearly published very detailed set of data for each of their facilities.Based on this exceptional database, we developed a home-made life cycle assessment tool, referred to as NELCAS (Nuclear Energy Life Cycle Assessment Simulation tool) to evaluate selected environmental indicators. We obviously considered the whole lifetime of any facilities, i.e. the contribution from the construction, the operation and the cleaning/dismantling, and every indicator has been normalized to the amount of electricity produced. We focused our analyses on the most widely used indicators, such as landuse, water withdrawal, atmospheric emissions (particles, GHG, SOx, NOx, radioactive gases), liquid release (effluents, radioactive release ) or different type of waste production. These data will be compared to other energy sources. Pros and cons of converting these data in actual impact indicator (Sv instead of Bq for instance) will be discussed in the paper.Furthermore, we were hence able to derive representative data for other fuel cycles type such as open fuel cycle or future fuel cycles. Based on the data published in the literature, we also introduced a potential average contribution from severe nuclear accidents based on Chernobyl and Fukushima data. Although the approach can be considered as controversial, it allows having an order of magnitude of such visible event on the most significant environmental indicators.The overall set of indicators will be presented and discussed as a function of the nuclear energy perspective, with a particular emphasis on the anticipated effect of any phaseout.