France did not experience a significant fall in construction costs when they were building lots of reactors in the 1970s. There's not much hope of getting that €125/MWh below €100/MWh, and honestly that €125/MWh is likely a sever underestimate to start with.
Don't know about France but TVO in Finland is way under that. Their earlier reactors were built in the 70s.
They have been hitting 15 to 20€/MWh for decades now. Or at least this is the price they have been selling to their owners without going bankrupt for decades now. Target with OL3 in the mix is 40€/MWh so OL3 alone is probably in the 50€/MWh to 60€/MWh range. (and they got a really good deal with OL3)
One big difference in the costs is that now days, new reactors are required to fund their own eventual decommissioning and long-term waste handling costs from operating income.
That wasn’t always the case! In the UK, taxpayers have been left with enormous liabilities for managing and cleaning up old nuclear sites:
Finland deserves credit for actually building a long-term waste storage repository, which helps solve one of the biggest ongoing issues/costs with nuclear decommissioning.
The operators have been paying into a fund since the 80s which is meant for decommissioning and spent fuel storage.
Basically it is a legal requirement (some small fraction of a cent for every kWh produiced)
This is really the only sane way to do it.
Also we got lucky with the ground under Olkiluoto being good spot for nuclear waste storage so not much NIMBY stuff for that as it is already the site for the biggest nuclear power plant in the country. It is also small town so a huge % of the population there work at the plant or its sub contractors.
Paid off reactors can get by on O&M only costs. The trouble is getting through that initial period of paying off the loan and interest. Also, older reactors were far simpler and reliable to construct. (Though "simpler" does not mean simple, they are still extremely complex beasts of machines.)
Finland was smart enough, and France dumb enough, to sign a fixed-cost contract for OL3. This ended up in complete disaster for the French companies doing the building, with the French government buying up the failed builder.
So you can thank French taxpayers for a €70-€100/MWh subsidy for the new clean energy in Finland.
What you're saying is just true of EPR, but not revelant at all in comparison to what happened when the nuclear plants where mass produced. As the parent said, nuclear has been very cheap for 3 decades.