Nuclear can also produce valuable process heat (was Low cost Launch)

My gosh, are we back to the Nuclear Gospel again? Can we identify 60 neighborhoods in the U.S. that would welcome a nuclear power plant before we go too far down this path for the umpteenth timelet alone 6,000?

>I can see 10-20,000 reactors replacing most fossil fuel, but I
can't imagine an additional 60,000 GW reactors being used to take
carbon out of the air.

Why would the number, or individual capacities, of the reactors be naturally limited? What is unimaginable about 60,000 GWe of fleet nuclear capacity?

Also, have you considered that, unlike SBSP, nuclear reactors can create process heat, in addition to electricity? That allows them to use more-efficient (e.g. than electrolysis) thermochemical processes such as sulphur-iodine...
http://en.wikipedia.org/wiki/Sulfur-iodine_cycle

...and thus allows them to be more efficient than SBSP, on an electrical-power basis. (E.g., one GWe of nuclear is worth more than one GWe of SBSP).