Actually the price of electricity in Finland is among the lowest in Europe. This is one of the chief reasons how our system works. You see, we have a lot of traditionally extremely energy-intensive industry related to forestry (i.e. paper, carton and cellulose production), metalworks (both smelting and advanced machining such as shipbuilding) and so on. As a result, one of the primary goals of the entire country's energy policy is to ensure that electricity would be as cheap as possible. This kind of forward planning is what allows for those record profits. Not electricity prices, that are very cheap in Finland by European standards to the point that it was one of the chief reasons why most of the heavy industry stays in the country, and why modern energy intensive industries like heavy datacenters (i.e. Google) find Finland so interesting for their European operations.
The thing is: Cheap electricity prices make nuclear (and everything else) less economical. So the question still is why should nuclear plants be more profitable in Finland than elsewhere. Weren't the current plants not build by a government-owned power company (Imatran Voima Oy) which was then privatized later? Considering this, I assume that the existing nuclear plants in Finland were probably not really economical, but if nobody does an audit of how much this government-owned power company actually has spent when building these plants this will never become apparent. Looking at old press articles about how Loviisa started out has a hybrid of Sowijet and Western technology and needed costly repairs and changes, I somehow doubt that it was so economical as claimed.
Some other things you should understand before arguing on the topic of "eating profits".
Ok. But my point was that you should not sectively pick the successful projects while ignoring the cost of the failures when discussing the overall economics of nuclear. If the French tax payers pick up the bill for that disaster this is certainly good new for Fins, but does not really make nuclear more economical in the overall scheme of things.