That is called the pressure vessel.
The core goes inside of that.
Bring a really big crane if you want to build really big stuff.
Near beautiful Waynesboro, Ga.
I occasionally ride through there when traveling from Savannah to Augusta (and back).
It’s a forest of temporary travel trailers and semi permanent housing for construction workers.
Having lived down river from the Savannah River Site, we aren’t too worried about this one.