An engineering model for hazard prediction of ammunition magazine doors

An accidental explosion in an ammunition magazine may break-up the structure and cause a significant debris hazard. Experimental and theoretical research mainly focusses on the break-up of the reinforced concrete or brick magazine walls. The behaviour of the door has usually been ignored in the derivation of Quantity Distances (QDs) and risk analysis. The study reported in this paper shows that although the door represents only one or just a few large fragments, the size, impact distance, and consequences of a hit, make it a relevant object to take into account. Within the Klotz Group (KG), available experimental data on slab and door launch velocities has been collected, as well as information about the ballistic behaviour and impact distance. Data from small and full scale magazine tests, with and without earth cover, have been used to validate an engineering model for the prediction of the launch velocity, and an analytical door trajectory model. The results show that observed launch velocities can be well understood with the semi-empirical DLV equation, and observed impact distances can be reproduced with realistic assumptions about ballistic behaviour. Uncertainties remain with respect to the deformation of a door and ricochet. For the storage of small quantities the door hazard is typically dominant compared to other explosion effects. A parametric study showed that in many cases door impact takes place outside the established Inhabited Building Distance (IBD). Whether QDs need to be adjusted to account for the door hazard depends on a number of aspects, including the size of the door and stochastic variation of the door launch direction in the horizontal plane. The results of this study stress the importance of preventing the launch of a door, such as by a door barricade. The results of this study can be used for further development of the KG Engineering Tool (KG-ET), by implementing the presented model for the prediction of door impact. The results can also be used for risk analysis and to support possible future updates to QDs within NATO AC/326.