In article ,
Paul F. Dietz wrote:
Likely recoverable reserves of U-235 (not counting seawater and granite,
both of which are very difficult to mine economically) ...

I don't understand why you say this about seawater uranium. Estimates
for the cost of extraction using the Japanese amidoxime technology
are as low as 10,000 yen/pound (with some development)...

"With some development." I say this because I'm deeply skeptical about
some of those development steps, especially the ones that don't appear in
the oversimplified treatments. "Reality is, there are a lot more boxes in
the diagram, all of which cost money." (Jordin Kare, talking about
something else entirely, but it fits here too.)

For example, I see no mention of the problem of keeping the collection
system free of barnacles and other sea life, a problem that's never been
fully solved even for ships.

Bear in mind that we're talking about doing chemical processing on an
enormous scale. To get 30 TW-yr worth of U-235 per year, assuming
complete recovery of U-235 from natural uranium, would require complete
extraction of the uranium content of about a cubic kilometer of seawater
per *minute*. I'm not aware of any chemical process -- not even
purification of drinking water -- which has ever been done on anything
like that scale.
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