Plus much of the cost of nuclear is tied with the construction of the plant not the operating costs, so a paid off plant isn’t particularly expensive.

I wish that were true. Nuclear plants built in the 60s and 70s (but still operating today) was losing money in Ohio. So the power companies bribed the Republican Ohio Speaker of the House $60 million dollars to pass a law that citizens have to pay extra fees totally over $1 billion dollars to power plants so that power companies can make a profit on nuclear. The bill was passed, and signed into law by the governor of Ohio, and years passed before the investigation found the bribery scandal.

That former Ohio Speaker of the House was sentenced to 20 years in prison finally.

The bad bribed-passed law is still on the books in Ohio and citizens are still paying extra to artificially make nuclear profitable for the power company. Here’s just a small source for the whole sorted story..

So no, even old built nuclear power plants are still more expensive that nearly all other electricity sources in the USA.