The empirical evidence has nuclear being uncompetitively expensive. The current focus on variant reactor designs appears to be something of a Hail Mary attempt to get around this sad state of affairs.
You sometimes see them making an argument about energy density, which goes back to Vaclav Smil. But Smil used this argument to massively mispredict how solar would be go in the market. We don't hear him much anymore.
Nuclear advocates increasingly resort to conspiracy theoretic reasoning to explain away the failure of their technology to compete. This should be a red flag.