Drop Testing Of A New Package Design For The Transport Of SNF From German Research Reactors

A new dual purpose cask design was developed for the safe transport and interim storage of spent fuel elements of German research reactors. In context with the relating licensing procedure and safety assessment in Germany the Bundesanstalt fuer Materialforschung und -pruefung (BAM) as competent authority performed a series of drop tests according to the IAEA-Regulations. The package consists of a cylindrical thick-walled ductile cast iron cask body closed by a double lid system with metallic seals. A lid and bottom sided impact limiter made of a wood/steel construction limit the mechanical impact loading. The full-scale test specimen was equipped with a basket and loaded with dummy-fuel elements. The package and test specimen, respectively, has a total mass of approximately 24 metric tons.The mechanical test program included three 9m-free drop tests, in horizontal, vertical and oblique cask orientation onto the lid system. Additionally, a 1m-puncture drop test followed the horizontal drop test in order to complete an IAEA-test sequence. The horizontal and vertical drop tests were performed at a temperature ofminus 40°C. During the oblique drop test the upper impact limiter was heated to +80°C. The tests were conducted onto an unyielding target, fulfilling the requirements of the IAEA regulations.The test specimen was considerably instrumented with strain gauges and accelerometers. Transient strains at selected locations of the inner and outer container walls, of the primary and secondary lid, as well as of the corresponding lid bolts were measured during the drop tests. Furthermore, decelerations in different locations at the cask body and the lids were measured. The complex geometrical deformation of the impact limiters due to the impact were determined by optical 3d- measurements using the projected fringe method in combination with multi-image photogrammetry. Before and after the drop tests the leakage rate of the lid system was determined by helium leakage testing.The experimental results contribute to the evaluation of the package response to mechanical tests, demonstrating safety under normal and accident conditions of transport and especially to the verification of the dynamic finite-element model of the package used in the package design safety report.