re: First? Depends on how you define it.
"Given modern reactor technology and the infrastructure already in place to support military ships, I wonder if nuclear powered large cargo ships would be financially practical again. Oil tankers?"
How about submarines? How about fresh water submarines parked in the great lakes. How about concrete submarines parked in about 100 meters of water. Have some sort of "quick connect" for high voltage power. These could be 10 or 20 miles from a city or any land.