Exactly: "One of those places." In the context of the film, Stark looks potentially smart because he intuitively guesses the right place; but we potentially read him as a little slow for not guessing sooner because we as an audience were shown this particular reactor already an hour before. An hour. If Stark is in something like the real world, with multiple power sources and a longer timeframe, he would have to either guess fast ("It must be my reactor because ....") or would need to eliminate all other possibilities, and possibly you get SHIELD splitting its forces to protect various power supplies around the world. A film of this length can't do that, so it takes the narrative shortcut - what the viewer can't do is judge thre intelligence of the characters on the basis of the "edited version of the story/world" that we see.
