How was Iran storing the enriched uranium? If these were just ingots, why couldn't they just dig them out of the rubble? Seems like uranium is used for armor

How was Iran storing the enriched uranium? If these were just ingots, why couldn't they just dig them out of the rubble? Seems like uranium is used for armor plating, so presumably pretty tough and heat resistant. Different story if it is in solution (uranium hexaflouride?) or in a non-metalic form. Although even in those cases, as long as you weren't storing it in the same area as your depleted stock, it seems like you could leach it back out of the soil and it would still be enriched. Right?