It is a good job the station's Finnish owner/operator, TVO, got it on a fixed price contract. That does not make coping with the delays in coming online any easier, but some consolation that someone else is footing the construction bill and enriching the local economy.
This is, to some extent, the same as Hinkley Point C where EDF and CGN have got a long term strike price. I wait with interest to see how Sizewell C will be financed, be it the regulated asset base model or else a Contract For Difference.
There is a good argument for cost-plus construction contracts provided the purchaser can financially cope with the risks. Risk transfer is never free!