[adgjlsfhk1]

this has some serious problems in the analysis. First of all, about half of the earth's crust is under an ocean. Second, of the remaining half, it is on average about 10 miles deep. There is no way that digging up 10 miles of rock to get to some scattered uranium atoms is net positive from an energy perspective. The deepest mines in the world are 2.5 miles under ground, and is in a location with a very high concentration of gold. Most of the uranium in the earth's crust is at concentrations of less than 1 part in 1 million, and one ton of uranium can only (being maximally optimistic) lift 1 million tons of rock by about 1 mile, so any uranium lower than that (not in a major vein) will produce negative energy to mine. Also, just because it's technically net energy positive, doesn't mean it's efficient at all. If we want mining to be at least somewhat efficient, we will only be getting roughly 1/3rd of that (since by the time you are lower, you will be losing too much energy to be cost competitive).

This very basic analysis suggests that your link is off by at least a factor of 100, which doesn't inspire much confidence in their results.

[pfdietz]

Ocean floor bedrock is basalt, which has much lower U/Th content than granite. Granites are continental rocks.

Geologically, U and Th have been concentrated over the billions of years by about a factor of 1000 in the minerals that have accumulated in continents. Were this not the case, fission power would be completely impractical.