France's nuclear power program actually displaced oil. France had a lot of oil fired electric power plants in the 1960s when it was a cheap fuel. As a reaction to the oil price shocks of the 1970s, France committed to the "Messmer Plan" for nuclear electricity:

https://en.wikipedia.org/wiki/Nuclear_power_in_France#Messme...

France demonstrated its first fission bomb in 1960 and its first thermonuclear bomb in 1968:

https://en.wikipedia.org/wiki/France_and_weapons_of_mass_des...

The 1970s and 1980s build up of nuclear power in France had nothing to do with desperation to have its own nuclear weapons. France already had them before the Messmer Plan.

"France's nuclear power program actually displaced oil"

No. Oil is much cheaper

To maintain a nuclear arsenal a nuclear industry is needed.

It is the only economic justification for nuclear power

So you don't think something can be expensive because it is heavily regulated? Or do you just think it is not possible with less regulation?

What is the point of bringing up economics when we are talking about life and death? How can you even measure if something is economic or not if you haven't defined what a human life is worth?