"Far too expensive" in what context? For whom? Short-sighted profit-seeking, growth-oriented capitalism got us into this mess and it certainly won't get us out.
For a long time, nuclear supporters just ignored the cost issue, since they felt they were the only real non-fossil alternative. Yes, they'd be expensive, but society had no choice. In the last decade this changed. Renewables are now far cheaper on a levelized basis, cheap enough that even with the cost of dealing with intermittency they are likely to come out cheaper than nuclear.
This is why so much new capacity in the world (and in the US) is renewables. It's not because of green mind control, it's because of brute economics. Nuclear is in dire shape competitively, in comparison.
But what are the costs of unstable supply and behavior of whole grid?