[posterchild]

Isn't Uranium Hexafluoride a gas at STP?

[verum ago]

Isn't Uranium Hexafluoride a gas at STP?

nope-- it sublimes at around 130° F

[Robert A Cook PE]

Uranium Hexafluoride is a gas (when pure), but it's not transported that way.

Transporting "tons of uranium" is like moving any low-grade radioactive substance or low level waste: at this stage it's a metallic mix or alloy, very low enrichment, with only a few tenths of a percent U235. a few percent U238 (inert), and the rest the alloying agent (like any ore, the "pure" stuff is mixed in with the 90%+ non-Uranium elements.

the mix is in the multiple-staged containers (against spills or truck accidents like this), and those are tested against simple flip-over accidents like this.

the High-radiation spent fuel containers are much, much more robust, and are actually tested by driving a train at full speed through the trailer, then keeping the resulting (dented) container in a fire for several hours, then checking for leaks. (None have.)

[GSlob]

"Isn't Uranium Hexafluoride a gas at STP?" - Low boiling liquid. And they were transporting a powder - oxide, probably.