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)
https://www.tvo.fi/material/sites/tvo/pdft/rm89bf734/TVO_-_C...
That wasn’t always the case! In the UK, taxpayers have been left with enormous liabilities for managing and cleaning up old nuclear sites:
https://www.theguardian.com/environment/2022/sep/23/uk-nucle...
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.
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.
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.