Impact Limiter Development and New Material Investigation for Spent Fuel Transport Casks

10 CFR 71 regulations require that the containment boundary of a transport package is able to withstand a 30 ft (9 m) free drop onto a flat, essentially unyielding surface. Impact limiters are designed to limit the deceleration experienced by the cask and its contents during the impact. Orano TN has used wood, typically balsa and redwood, as the material of choice to absorb the energy from the 30 ft (9 m) drop. The light weight and high energy absorption capabilities of wood make it an ideal material used for impact limiter fabrication. This paper presents the lessons learned during the impact limiter fabrication at TNA and the impact it had on design and licensing. Benefits of an engineered material as an energy absorber are investigated and compared with wood. An impact limiter design path is proposed. Main topics include:Issues discovered during fabricationChanges to the requirements used to resolve issuesAluminum honeycomb investigation and performance comparison with woodFuture design suggestions