PROTECTION OF FACILITY AGAINST MALEVOLENT ACTS TECHNICAL TOOLS FOR THE VULNERABILITY STUDY

As required in the French regulations, the behavior of the nuclear fuel reprocessing or fabrication plants and nuclear power plants must be assessed for a set of various normal and accidental situations including explosions due to operation hazards or malevolent acts. In this last case, the assessment gathers both safety and security aspects and lead to undertake studies accounting for loads due either to an explosion resulting from an aggression with a large amount of explosive or to an attack with a High Energy Density Device as a conical shaped charge. In order to provide the Authority with elements of appreciation and in support of the expertise of the studies performed by the operators, the Institut de Radioprotection et de Sûreté Nucléaire has initiated a program including experiments and development of numerical models concerning the evaluation of the consequences of such aggression in terms of mechanical damage to the plants and radiological release in the environment. This paper follows the general paper devoted to the French approach for assessing the consequences of malevolent acts, which is based on a sensitivity study aiming at determining the critical components, followed by a vulnerability study for assessing the behavior of the facilities, depending on the type of weapons chosen in compliance with the threats. So for introduction, it will briefly recall this approach. The paper will focus on the technical tools to perform the vulnerability study in the case of an aggression by explosion. Then three examples concerning a pool, a chimney and a building will be presented. The first example is the study of a rectangular pool or tank with walls made of reinforced concrete, when an explosive located inside the pool is detonated. The second one is dedicated to a long chimney with a large room at the bottom which is subjected to an internal explosion at the junction between the room and the chimney. The third one is the behavior of a building subjected to an external explosion with a large amount of explosive.