If you factor in all the cost usually externalised in nuclear power, it’s often a lot more expensive than people realise. Decommissioning nuclear waste and old reactors is a huge, time-consuming, and thus extremely expensive operation.
This turns out not to be the case, and all these supposedly "externalized" costs are actually included in the price of electricity produced by nuclear reactors.
For example in Switzerland, all of that still allows full production costs of 4,34 Rappen (with a profit).
The only wrinkle is that when the German government made electricity production from nuclear power illegal, it had to take over some of those responsibilities, for obvious reasons.
It also took over the money that had been saved up thus far, which is almost certainly more than needed to cover the costs. Well unless those costs are driven up to infinity with ever more creative mechanisms by politicians.