In response to the consequent events at Fukushima Daiichi Nuclear Power Plant following the 11th March 2011 Great East Japan Earthquake, the French electric utility company EDF launched a seismic re-assessment program implementation in accordance with the French Nuclear Safety Authorities. This program, called SND (S é isme Noyau Dur), aims mainly at reaching safety objectives concerning the resilience of the SSC (Structures, Systems & Components). End of 2015 matched with the end of the first whole re-assessment of a still operating Reactor Building (RB) in France, for which innovative thinking have been necessary to optimize current methodologies and assess in detail the civil work robustness and the induced vibrations under high level of earthquake, corresponding to site SND. Through the presentation of the keys hypotheses and methodologies used to carry out this significant study, a review based on the Tractebel and EDF knowledge of the French Reactor Buildings will propose some leads to adapt the future SND program to other Reactor Buildings.