It could happen:
There are many things people do not want to be built in their backyard, and nuclear power stations are high on the list. But what if floating reactors could be moored offshore, out of sight? There is plenty of water to keep them cool and the electricity they produce can easily be carried onshore by undersea cables. Moreover, once the nuclear plant has reached the end of its life it can be towed away to be decommissioned. Unusual as it might seem, such an idea is gaining supporters in America and Russia. …
The American researchers think there is no particular limit to the size of a floating nuclear power station and that even a 1,000MW one—the size of some of today’s largest terrestrial nuclear plants—could be built. They believe the floating versions could be designed to meet all regulatory and security requirements, which would include protecting the structure from underwater attack, says Dr [Neil] Todreas.
The Dish 