DELAYED IMPACT OF THE CONTENTS OF A TRANSPORT PACKAGE FOR NUCLEAR FUEL

It is a phenomenon that impact load applied onto lid from content with a gap between content and lid could be several times as larger as the one without gap under lid side vertical drop test. As the gap generates a time lag of impact of body and content, the phenomenon is called as “Delayed Impact”.At the previous PATRAM 2013, we have ever presented the mechanism of the Delayed Impact with FEM analysis results. The analysis has been carried out with initial gap 0mm, individual gap and the maximum initial gap 20mm to show different reaction forces due to different initial gap. It is observed that the reaction forces due to both individual gap and the maximum initial gap 20mm have nearly same value as well as tendency.In this study, we have carried out some additional analysis with as same condition as previous one and extracted stress of lid bolt and opening of lid to observe the leakage situation. It was observed that some plastic strain and residual opening have occurred. In order to reduce the delayed impact load, it might be considered to size down the gap or lower the impact load. There is a limit to size down the gap because it is set for absorbing thermal expansion of content. Finally it has been found that installing spring in the gap can be an efficient way to lower the Delayed Impact.