Since the Toulouse accident (2001), the French Authorities have emphasized the position of the Safety Study in the risk management process. In this new context induced by the promulgation of the law n°2003-699 of 30 July 2003 about the "prevention of the technological and natural risks and to the compen-sation of the damages", the Safety Studies performed by the industrials is : a demonstration of the risk control ; a support to the urbanization control around Seveso sites using Technological Risk Prevention Plans TRPP. Different categories of actors, such as general manager, operators, contractors, central and local Ad-ministrations, associations, etc., are involved in the risk management process making it more complex. As a technical support to decision-makers in risk prevention from both public and private sectors, INERIS plays an important role in the evolution of the French risk prevention plan. This paper aims at revealing the differ-ent decisional and expertise problems faced during the Safety Study and the Technological Risk Prevention Plans.