u/Gusfoo

Project Sapphire was a secret mission carried out by the US and Kazakhstan in 1994 to remove a large stockpile of 1,322 lbs (600 kg) of 90% highly enriched uranium. This uranium, planned to fuel cancelled Alfa-class submarines, was enough for roughly 20 bombs and had been stored in a poorly secured warehouse at the Ulba Metallurgical Plant in Kazakhstan. The security consisted of a "Civil War padlock" and the HEU was stored in buckets placed on plywood platforms with documentation on dog tags. The US flew in 3 C-5 Galaxies to carry the total of 4,850 lbs of material, which included the HEU and other material, some contaminated with beryllium, stored in 448 containers. It eventually arrived at Oak Ridge in unmarked Safe Secure Transporters from the DoE's Office of Secure Transportation.

Some comparisons have been made to a possible US mission in Iran against the Isfahan facility which stores much of Iran's 60% HEU, however this is a very different situation. Obviously, it is harder to do with people shooting you, and it is also buried under a mountain with the tunnels sealed. If the US does make a deal with Iran that would permit the US removal of HEU, as has been claimed by the US government, then we would probably see something similar to this.

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