EVALUATION OF SEVERITY OF DROP TESTS ONTO REAL TARGETS

IAEA transport regulations require the 9m drop test for type B packages. This drop test is required to confll1ll the integrity at impact in an accident during transport, such as a drop accident or a traffic accident. The target used in this drop test must be unyielding. However, the real target that the transport package might encounter in an accident during transport is a yielding target, such as concrete, asphalt or soil. To compare the impact acceleration between a real target and an unyielding target, analyses of the drop test onto a real target and an unyielding target were made. The evaluation was performed for a spent fuel package. The computer code used in the analysis was \"DYNA-30\". The structure under the real target was modeled according to a typical road structure. The drop heights were parameter, which cover some representative real accidents. The analysis was made and the acceleration for each target was obtained. The results were evaluated by using the acceleration for each target. It has become clear that the drop height onto the road corresponding to the 9m drop height required by IAEA regulations is about 47m for concrete road surface and is about 51 m for asphalt road surface, the impact velocity is about 30m/s for both road surfaces. In case of soft soil, the drop height corresponding to IAEA regulations is about 71 m, the impact velocity is about 37rnls. During normal handling and transport, the package hardly ever encounters these heights and velocity. So It is judged that the drop height required by IAEA regulation is appropriate test condition.