> French nuclear supply chain atrophied quite lot in the last 30 years.

Because today it makes no economic sense. Supply chain for horse carts is also very atrophied.

>The South Koreans build Barakah nuclear power plant 5600 MWe for $32bn.

Still very expensive. Flamanville is an extreme when things go really bad, but 175 MWe for 1 bn is also very high. 1 bn buys ~1 GW of solar, ~1 GW of onshore wind, or ~3 GW of battery capacity. You should only build new nuclear either to get a better mix in the grid (up to 5% is the nuclear lobby recommendation), or because you have no sun and no wind.