Who says you can't sell a nuclear power plant?

If the project is successful then it makes money and doesn't have to be sold. If it doesn't make money then there is no reason to buy it. The business model is locked in regardless of who owns it on paper.

Just because someone owns a thing that makes money doesn't mean they don't need to ever sell part or all of it. They could need money somewhere else in their dealings. Generally utility providers have stable values but that is beside the point.

I am talking about a situation where a developer is unable to repay their debts due to an unsuccessful project. The assets may still have some value, but probably far less than the debt. And any buyer would have to believe that they can succeed where the original developer failed. That may still be possible but the list of potential buyers is very limited.

Also, the amounts of money are so vast that they would stretch most companies. Without massive cash reserves you are back to raising capital and the problems discussed.