Civilian nuclear waste is transported in hilariously overengineered steel containers.
(military nuclear waste is used to power the machines keeping Hyman Rickover alive deep under the Naval Reactors offices)
If you were mental, you might ask why we don't transport nuclear waste by air instead of by truck or train. Thankfully, the US government in its infinite wisdom has considered this scenario. For your reading pleasure, 10 CR 71.74;
It's a shame nobody has tried to transport waste by air, because the crash test videos of a steel canister smashing into a concrete wall at better than a third the speed of sound would be fucking sick.
Honestly, designing an unyielding target to withstand the canister smashing into it at 129 m/s would be a pretty solid engineering exercise by itself.