THE USE OF IMPACT ANALYSIS IN LICENSING AN INDUSTRIAL CONTAINER FOR TRANSPORTING NEW FUEL

The Finite Element Method (FEM) is a powerful tool for the simulation of mechanical and thermal behaviour of structures. In recent years, the explicit FEM has increasingly been used in the development of transport packages and as part of approval applications to demonstrate the performance of packages. Testing and analysis are the two methods specified in the IAEA Regulations for the Safe Transport of Radioactive Material for demonstrating the structural and thermal performance of a transport package against the requirements of the Transport Regulations. The roles of testing and analysis, and the relative prominence of the two, may vary between Competent Authorities in different countries. This can range from analysis being regarded as the primary mode of demonstration with testing as confirmatory, to testing being the primary mode of demonstration supplemented by analysis. This paper describes the use of the non-linear finite element code LS-DYNA in the licensing of a new container for the transport of new nuclear fuel. The package was classified as an Industrial Package (Fissile) in accordance with the IAEA Regulations, and hence it was necessary, among other things, to demonstrate that criticality criteria were satisfied under postulated impact conditions. Physical drop tests were carried out and the results are compared with LS-DYNA computer calculations using the same finite element (FE) models developed to support the design of the new container. The analyses and tests clearly demonstrate the novel use of polyurethane foam as the container main energy absorber. The FE predictions are compared for accelerations, bolt loadings and global deformations of the container. In general good correlation was obtained between predictions and tests and the differences, which did occur, particularly for accelerations, are discussed and reconciled. The paper concludes that explicit analysis codes are now so reliable for container impact calculations that minimal test work should be pursued basically for key confirmatory impact scenarios.