Re: Question for Daniel Lavigne (among others)

"G. R. L. Cowan" <[EMAIL PROTECTED]> wrote in message
news:[EMAIL PROTECTED]
> Fritz Schlunder wrote:
> >
> > about breeder reactors ...
> > are they not a feasible technology
> > that could eventually free us of fossil fuels?
> >
> > What are the opinions of other readers in this newsgroup?
>
>
> Breeder reactors that are cooled with liquid sodium
> have an interesting, although rather unimportant,
> advantage over the water-cooled ones that do the bulk
> of today's carbon-emission-free electrical generation:
> iodine binds strongly to sodium,
> and sodium iodide is an involatile compound,
> much like the familiar sodium chloride.
>
> So in sodium reactors the radio-iodine pathway
> to accidental exposure of plant neighbours
> has one more barrier, a very reliable one.
> A liquid metallic sodium surface, so to speak,
> never sleeps in its vigilant watch for halogen.


Interesting.


> The scarce-uranium part of the story that justified
> breeder prototypes never made any sense.
> A US dollar buys ~40 grams of natural
> uranium and in today's burner reactors, e.g. CANDU,
> with no reprocessing, that makes > 2 electrical megawatt-hours.
> The uranium mining cost is less than US$0.0005/kWh.
>
> Breeders, with reprocessing, can reduce that to US$0.000005/kWh
> but to date, at prototype scale, have increased total costs.
>
> Raising the price offered for uranium mining
> to a penny or two per kWh
> would yield at least tens of gigatonnes of it.
> See "World Uranium Resources"*, Kenneth S. Deffeyes and
> Ian D. MacGregor, Sci. Am. January 1980.
> It shows on page 74 a plot of seawater
> and other low-grade ores.
> The bar for "Black Shales" is 30 billion tonnes
> high and centred at 0.006 mass percent uranium.
>
> So uranium scarcity cannot, for at least several thousand
> years, close down burner reactors like today's.


Certainly tremendous quantities of natural uranium exists in the sea and
ordinary continental crust, but is it ever going to be realistic to
economically extract most of it?  On the first page of the foreward of the
book "Fast Breeder Reactors" by Alan E. Waltar and Albert B. Reynolds (C
1981) they lead the reader to believe that the energy content of 70 parts
per million uranium ore is approximately that of coal when burned in a
conventional reactor.

But then if you read the book "Nuclear Electricity" 7th ed. by Ian Hore-Lacy
available online at:

http://www.uic.com.au/ne.htm

And then check out chapter three:

http://www.uic.com.au/ne3.PDF

They suggest seawater has a natural uranium concentration of a mere 0.003
parts per million, or 3ppb.  That seems like such a truly pitiful number I
can't imagine seawater (or regular dirt for that matter) ever being a
practical source of uranium.  If the 70ppm ore has approximately the same
energy density (when burned with conventional reactors) as coal, then that
would suggest sea water has a rather negligible energy density.  Does
technology exist that can extract the uranium from sea water that doesn't
take more energy than the uranium extracted could ever generate?  If it
does, could you point me to a place where I might start reading about it?