Seawater extraction is a C&B move:...

Seawater extraction is a C&B move: http://large.stanford.edu/courses/2018/ph241/voigt1/

”Not only is extraction difficult, it is also very costly. Separating the uranium ions from other more abundant metal ions requires high affinity, selectivity and the ability to deal with an enormous volume of water. [6] This has presented several design and physics challenges which a few physicists have explored. Japanese research suggests the lowest possible cost to extract uranium is 25,000 Yen per kilogram of uranium or 230 USD per kilogram of uranium (at current exchange rate April 2018, 1 USD = 108 JPY). The price of this uranium is 3 times more than the current price of uranium, and it is expected that the actual recovery price would be about 10 times the current price of uranium.“

You’d have a better chance of viably extracting uranium from one of my farts after a big night on the tinnies.