Magically cheaper nuclear powerplants, presumably built by the Nuclear Fairy.
The cost of steam turbines and generators alone would prevent nuclear plants from producing power at 1/10th the cost of current plants. I don't think you're going to find a nuclear component of the plant that costs negative dollars.
In the US, nuclear plants were being sold at a price competitive with coal plants. But that wasn't because that was what it cost to build the plants, it was because the vendors were setting the price to compete with coal plants, with the hope that costs would come down with experience (which didn't happen).
These turnkey contracts cost the nuclear vendors a lot of money, and they moved away from them for that reason. Only in the last wave did Westinghouse go back to these kinds of contracts, and it drove them to bankruptcy.
Well, in the link above there is a very clear take as to why that happened; in particular regulations were pushed to be way over stringent than needed by nuclear service companies themselves.
regulations were changed retroactively as well, for already approved projects.
What that first link claimed was "By 1965, large-scale power plants were being sold commercially at costs competitive with fossil fuel plants."
And I explained why that was misleading. They were being sold at a loss. The PRICE was competitive with coal, but the cost was not. This was even before changes in regulations.
The Turnkey Era in Nuclear Power, H. Stuart Burness, W. David Montgomery and James P. Quirk, Land Economics Vol. 56, No. 2 (May, 1980) (available through JSTOR)
The latter is interesting, as it also gives an explanation for why utilities might have liked non-turnkey contracts: any escalation of capital cost can be (and very often was) passed on to ratepayers. In light of this, what really nailed the first US nuclear age was the passage in 1978 of PURPA, particularly the part about non-utility suppliers.
The key point here is the perverse incentives of regulated monopolies. If the monopoly can get the regulators to agree, then the more capital intensive something is, the more money the utility makes. They do not have an incentive to keep costs down.
