Because the "Fear Mongers" won at the U.S., the U.S. now lags behind most of the World's Nations in the development of Safer Nuclear Power and only has 1960s to 1979s designed Nuclear Power, while the Rest of the World is going to 21st Century Nuclear Power that was originally designed by the U.S. during the 1950s.
During the 1950s Safer Nuclear Power was created by the U.S., the reason why this was not used, was because this Safer Nuclear Power did not produce Weapons Grade Uranium and Weapons Grade Plutonium like the Current U.S. Nuclear Power Plants produce for the U.S. Nuclear Weapons Program.
The U.S. currently has about 104 Nuclear Reactors that are of the Unsafe Design, at other Nations, this U.S. Unsafe Design has proven to be Unsafe, like the Nuclear Reactor Disaster at Fukushima. The Safe Design uses less Nuclear Materials, physically shuts down it's self in the event of a failure and uses Nuclear Waste as Fuel (like the Nuclear Waste Stored at the U.S., including depleted uranium).
These Safer Nuclear Reactors, that some call Thorium Nuclear Reactors or "Liquid Metal Cooled", Must Be Built, made Operational, then the Older Nuclear Reactors torn down.
The other Nations have already begun, including China, India, and Some Third World Nations putting the U.S. near Last Place as far as High Technology Solutions, that the U.S. actually successfully tested for over 30 years. Shame on you "Fear Mongers", you screwed over Future Generations' Renewable Energy, and being able to live at a Safer World, including getting rid of Nuclear Waste, not burying that all over the place.
Reference: PBS NOVA "The Nuclear Option".
Just for entertainment (and some education) watch the Norwegian TV Series "Occupied" Okkupert, this depicts the Results and Reactions to Norway's creation of Safe Nuclear Power, Thorium Nuclear Power.