For Olkiluoto 3 TVO got the original 3.2 billion from its owners and some loans. And it was a fixed price contract but TVO has given into Areva a bit and is now projecting that it will cost them 5 billion. Areva at the moment projects the total price to be 8.5 billion so they will be taking a loss on it (who is going to pay what part of the overruns was in some courts at one point haven't really followed up if there was some verdict and what it was)

Funnily enough most of these loans are from German banks and various export agencies backed by the French government. Even still all these loans were given at market rates so EU would not kill the project (Greenpeace etc did make a complaint to EU and a investigation was done)

This kind of seller arranging some part of the loans is very normal in large infrastructure projects like these.

The other new project I mentioned is Hanhiviki in which Rosatom won the bidding. Areva and Toshiba also left their bids but as I understand it Areva was thrown out due to their failure to deliver Olkiluoto 3 in time/budget and Toshibas bid was not competetive. Though this Hanhikivi plant is still waiting for permits and there has been some obvious issues with it being built by Rosatom and the Russian sanctions going around. It also has some American and UK interests as Rosatom contracted the turbines to some GE subsidiary and Rolls Royce.

https://en.wikipedia.org/wiki/Hanhikivi_Nuclear_Power_Plant