MECHANICAL IMPACT ASSESSMENT OF CUBIC WASTE CONTAINERS DEPENDING ON TARGET CONSTRUCTION

BAM as the German competent authority for design testing of transport and storage packages for radioactive materials performed design tests (representing a handling accident inside a repository) with a cubic container made of ferritic ductile cast iron (DCI) with outer dimensions of2.0 m x 1.7 m x 1.6 m, a wall thickness of 150 mm and a maximum gross weight of20 Mg. Current results of very extensive experimental and numerical stress analyses for a drop from 5 m height flat onto a real target without additional impact limiters are presented. The investigated real target consists of a concrete slab put onto the 1000 Mg IAEA target with a layer of wet sand in between. Several drop tests with a fully instrumented prototype container have shown a highly dynamic behaviour of the container structure with maximum stresses up to the yield stress (Droste et al. 1992). The detailed strain measurement data are compared with numerical finite element stress calculations. The experimental and numerical analyses show a contact duration of approximately 5 ms. The deformation of the container is mainly characterized by bending respectively bending vibrations of the container walls. Highest demands on the cubic container structure were found in the vicinity of inner comers and edges, in the middle of the walls and especially of the container bottom plate.