BEHAVIOR OF TRANSPORT CASKS UNDER EXPLOSIVE LOADING

The behavior of the casks used for shipping nuclear material must be assessed for a set of various normal and accidental situations. Though not explicitly required by French regulations, the security of the casks must be studied from the viewpoint of the loads imposed by an explosion such as induced by aggression involving a large amount of explosive. In order to evaluate the consequences of such aggression in terms of damage to the cask and radiological release into the environment, IPSN has launched a program including experiments and the development of numerical models concerning a cask used for the shipment of PuO2 powder. Experiments were carried out using simplified reduced-scale mock-ups representing a multi-layered cylindrical cask, and allowed evaluating the influence of the reduction ratios and the type of explosive. These experiments showed that the inner cylinder containing the PuO2 powder remains intact Numerical 2D models, employing two orthogonal planes representing the cross section of the device comprised by the explosive and the cask, were developed to understand the physical phenomena occurring during the interaction between the shock wave and the cask. This approach, combining tests and numerical models, allows limiting the need for costly experiments, since these models can be extrapolated over the corresponding range of validity, to cover casks having similar geometry or to different loads (amount and type of explosive). Moreover, IPSN has proposed a multiyear program whereby the approach may be extended to various kinds of casks and aggression types.