From Google...The Superdome is a massive structure located on 52 acres of land; a height of 253 feet, a dome diameter of 680 feet, making it the largest domed structure in the world.
The Superdome is built to withstand catastrophes; the roof is built to stand up to 200 MPH wind and even deep flood water wouldn't reach the second level 35 feet from the ground. It has thus been used as an emergency shelter but is not designed for the task; in 1998 during Hurricane Georges problems included looting and supplying 14,000 people with necessities.
Not to mention no electrical power.
Key words: "...up to..."