"The mock-up, which American officials described as more like a barge than a warship, has no nuclear propulsion system..."
Duh, how could it have nuclear propulsion when two-thirds of the world's diplomats and spooks (the USA's own plus its faithful servants, that is) spend most of their time ensuring that Iran never gets any nuclear technology, no matter how simple and peaceful?
OTOH, a moment's thought reveals that it doesn't need nuclear propulsion, whose main advantage is the ability to sail around the world several times without refuelling. It's unlikely that Iran wishes to indulge in "force projection" in the Gulf of Mexico or the Pacific, since it's actually a very peaceable nation. (Please check the history books before violently disagreeing).