Abstract: An impact amelioration system for nuclear fuel storage components in one embodiment includes a fuel storage canister and outer cask receiving the canister. The canister is configured for storing spent nuclear fuel or other high level radioactive waste. A plurality of impact limiter assemblies are disposed on the bottom closure plate of the cask at the canister interface. Each impact limiter assembly comprises an impact limiter plug frictionally engaged with a corresponding plug hole formed in the cask closure plate. The canister rests on tops of the plugs, which may protrude upwards beyond the top surface of the bottom closure lid. The plugs and holes may mating tapered and frictionally engaged surfaces. During a cask drop event, the canister drives the plugs deeper into the plug holes and elastoplastically deform to dissipate the kinetic impact energy and protect the structural integrity of the canister and its contents.

Abstract: A natural passively cooled ventilated cask includes a cavity which holds a canister containing heat and radiation emitting spent nuclear fuel assemblies. Cooling air inlet ducts draw ambient cooling air inwards into a lower portion of the cavity. The air heated by the canister flows upwards along the canister and is discharged from at least one air outlet duct formed by the cask lid to atmosphere via natural convective thermo-siphon flow. The air inlet ducts or at least one outlet duct in one embodiment may be fitted with an adjustable shutter plate which allows the flowrate of air entering the cask to be increased or decreased to maintain a predetermined canister maximum temperature limit selected in part to prevent the onset of stress corrosion cracking of the canister welds. Other embodiments may use a fixed orifice plate replaceable over time to maintain the minimum temperature.