I don't think that's correct. All you need is to enrich uranium, which is found everywhere.
https://en.wikipedia.org/wiki/Uranium#Occurrence says:
> Uranium is a naturally occurring element found in low levels in all rock, soil, and water. It is the highest-numbered element found naturally in significant quantities on Earth and is almost always found combined with other elements.[12] Uranium is the 48th most abundant element in the Earth’s crust.[60] The decay of uranium, thorium, and potassium-40 in Earth's mantle is thought to be the main source of heat[61][62] that keeps the Earth's outer core in the liquid state and drives mantle convection, which in turn drives plate tectonics.
> Uranium's concentration in the Earth's crust is (depending on the reference) 2 to 4 parts per million,[11][22] or about 40 times as abundant as silver.[17] The Earth's crust from the surface to 25 km (15 mi) down is calculated to contain 10¹⁷ kg (2×10¹⁷ lb) of uranium while the oceans may contain 10¹³ kg (2×10¹³ lb).[11] The concentration of uranium in soil ranges from 0.7 to 11 parts per million (up to 15 parts per million in farmland soil due to use of phosphate fertilizers),[63] and its concentration in sea water is 3 parts per billion.[22]
> Uranium is more plentiful than antimony, tin, cadmium, mercury, or silver, and it is about as abundant as arsenic or molybdenum.[12][22] Uranium is found in hundreds of minerals, including uraninite (the most common uranium ore), carnotite, autunite, uranophane, torbernite, and coffinite.[12] Significant concentrations of uranium occur in some substances such as phosphate rock deposits, and minerals such as lignite, and monazite sands in uranium-rich ores[12] (it is recovered commercially from sources with as little as 0.1% uranium[17]).
Now, 0.1% uranium is 1000 parts per million, which is a lot more than 0.7 to 11. But that doesn't mean current technology is incapable of recovering uranium from these 300× lower concentrations. It's just that it requires processing 300× as much rock, which is expensive, so it can't compete in the market with more concentrated sources.