This thesis is the result of almost 4 years of research carried out within the IRSN, one of the actors among the different actors in charge of nuclear crisis response. We started with the following question: how France gets prepared to manage a nuclear accident situation and what are the results of this preparation in a real accident case even if it is a minor accident or if it happens abroad ? Thanks to a very fruitful documentary and in field research work, we are able to show in this thesis that the unilateral management of a "crisis" situation by the different actors organized under the leadership of high level engineers from the 'Corps de mines ", results in a very technical definition of the "crisis " focused on the technical aspects while disregarding the general public. As a consequence, emergency drills that are defined and carried out do not prepare intervention teams to manage social reactions that may be caused by a nuclear accident. To the opposite and paradoxically, such a vision that neglects the reaction of the population may generate by itself a crisis situation even when an accident is deemed to be "technically" of a minor importance. However the management system of nuclear crisis is evolving. Organizational changes in this area that progressively take into account the social factor, really result from the in field experience of dealing with the general public reactions during a real nuclear crisis. Crisis training and drills have a lesser impact on this evolution.