>...I would have expected that the ratio would be much higher.
And you are right - the land needed to actually generate the power is much different than that ratio.
The strata report is also counting the land use for transmission lines which is a big part of the land use for any power source and makes the land use for different power sources look much more similar than they are.
From the report:
>...Because nuclear energy accounted for 19.55 percent of the nation’s electricity production in 2015, approximately 938,388 acres of land were used to transmit nuclear energy in 2015, or 10.312 acres per megawatt.
So of the 12 acres they attribute per megawatt for nuclear, 10 acres of that is for transmission lines which are going to be needed no matter the source of power.
The report gives an example later:
>...The Arkansas Nuclear One Station requires only 1,100 acres (1.7 square miles) to produce 1,800 megawatts operating at a 90 percent capacity factor. A study by Entergy Arkansas estimates that for modern wind and solar plants operating at the same capacity, they would require 108,000 acres (169 square miles) and 13,320 acres (21 square miles) of land respectively to produce the same amount of power.
https://www.strata.org/pdf/2017/footprints-full.pdf
As another data point, in a report on the Diablo Canyon nuclear power plant, PG&E reported:
>...To build the equivalent of a 1,000-Mw nuclear plant, a solar park would require 11,000 acres of PV solar panels and a wind farm would need 50,000 acres of wind turbines. By contrast, Diablo Canyon is able to produce twice as much power (2300 Mw) in a footprint of approximately 545 acres.
http://large.stanford.edu/courses/2016/ph240/hyman1/docs/may...
(Land use isn't the only factor obviously, but it is a factor.)