New Generation of Transport Cask for Used Fuel Assemblies – TN®-G3 Breakthrough New Drop Test Program

TN International has vast experience in domestic (in France) and international transport of used fuel assemblies. Up to 2,400 fuel assemblies are transported every year from EDF Nuclear Power Plants to the AREVA La Hague recycling facility. The TN®-G3 package currently under development will ensure these shipments for the next 40 years.It is designed to comply with the latest regulations and the more demanding requirements of the French Competent Authority such as the double-leak tight barrier and the delayed impact effect. The leaktightness of the double barrier in accident conditions of transport is one of the key criteria for the safety demonstrations. The TN®-G3 drop test program is based on an extensive calculations program reviewed by the French Competent Authority. The program is not just copied from previous packages. All possible drop test configurations have been studied so as to challenge the lid leaktightness and to maintain shock absorber integrity during the drop tests. For each selected configuration, the drop angle, impact line on the cask, were evaluated to maximize the drop effect. Dynamic calculations with FE models were made, in particular to verify the influence of material data scattering. The 1:3 scale drop test mock up was designed to be representative of all TN®-G3 packages to be manufactured. The drop test mock up geometry and the structural characteristics of the materials were downgraded compared to the full-scale package to take into account the effects of temperature on mechanical properties and also on scattering due to procurement specifications. The drop test campaign took place in 2014-2015 at the Areva TN test facility. Innovative drop test configurations are discussed below, such as the drop test with delayed impact, and the “wide-angle” side drop test.