I like this better, in order for the carbon chamber to fit inside of "the processing vane" that's going to have to be a pretty beefy width. Not to mention later in that scene we see a lot of winding hallways. I'm a little confused how they could be winding when the vane appears to be straight from the outside. Like I said in an older post, I think this was just a case of George Lucas overindulging in his obsessive compulsions to do whatever he wants with no consideration for logic or geography.
