I'm not finding much support costs being that low... best collection of info I have seen is here:

https://www.construction-physics.com/p/why-are-nuclear-power...

At 1.5-1.7x the cost of diesel ship, and the "well-managed" Virginia class costing $3.6B, we are at over $1B for 60MW of power, 200MW thermal, which is far worse than larger civilian reactors per watt.

The reason we use nuclear submarines and aircraft carriers are their far superior operational characteristics when compared to hydrocarbon fuels. That benefit is massive and well worth it. For terrestrial grid electricity those benefits don't really exist.