10 years? You're being generous here. Flamanville has been under construction since 2007, so at least 15 years for construction itself, and anything from 5-10 years for planning, acquiring land, relocation...
No, the best time is to spend the first mover costs on renewables in the 50s through 70s instead and then never build nuclear (or in the 1910s instead of spending them on coal and oil). The second best time is to build renewables now that those costs have been paid over the last 20 years.
Mjhay is correct. Anti-nuclear activists have successfully managed to use the government to stop nuclear energy construction for decades. It is entirely a political problem, not a technical one.
