Re: "Nuclear energy 'not the solution to global warming"

On Apr 21, 2:03 am, T. Keating <tkuse...@xxxxxxxxxxx> wrote:
On Thu, 19 Apr 2007 16:45:09 -0500, "Paul F. Dietz" <d...@xxxxxxx>
wrote:





T. Keating wrote:

They deferred that claim to your link..
http://nuclearinfo.net/Nuclearpower/UraniuamDistribution
which is titled "Uranium Distributions in the Earths Crust"

Note the claim "Earth's Crust".

70% of the earth's surface is underwater and completely out of reach
of current mining techniques. What's left has an average water
table in less than ~100m range, (Mostly out of reach, earth's crust is
30 to 40km ).

Actually, the rock of the oceanic crust has a much lower level of uranium than
the continental crust. Uranium (and, to some extent, thorium) preferentially
go into felsic rocks in preference to mafic rocks. The concentration
of uranium in the continental crust is enriched by orders of magnitude
over the average U content of the Earth because of this.

Assumes facts not supported by any evidence. (authoritative links??)

I.E. We haven't explored very much of the ocean bottom due to he
extreme cost and during the ice ages sea level was significantly
lower.

Repost crust thickness citation from my previous post..http://earthquake.usgs.gov/research/structure/crust/index.php

The water table objection is silly. Mines are often operated below
the water table in an area, using a wonderful technology called a 'pump'
to keep them dry.

NOT...

A portion of the recent Yellow cake price hike is due to major
flooding in two of the high yield ore operations(Canada, Australia).
It's going to take them year(s) to plug the breaches and pump out the
water.

http://www.bloomberg.com/apps/news?pid=20601082&sid=acsmdypplxBM&refe...http://energy.seekingalpha.com/article/29263

http://www.huliq.com/18027/australia-uranium-price-jumps-after-mines-...

Once you get into the lower grade ores, the energy you expend in
pumping water(24x7) will exceed the useful energy content of the ore
retrieved.

The first steam engines were designed to pump water from mines.

So what, EROEI quickly drops to a very low value as one chases lower
and lower grades of U ore.



Over the very long term, even the deep crust can be mined. Just remove
overburden and allow the area to float up by isostasy. Cool and mine.

The scale of such an effort is WAYYY beyond humanities limited
abilities. Besides being insanely dangerous.. (I.E. Triggering a
Super volcano eruptions.)..

It would dwarf ALL of the current ore mining efforts in the world,
making them look like a drop in the bucket.. Then you've still got
to refine the ore, which takes enormous amounts of other chemicals and
remove ALL the byproduct several

4000 x 1GWe plants would need about 1 Million tons of U ore per year.
At 20ppm U concentration that would require mining, refining, and
then moving 100 BILLION tons of raw material per year. Obtaining the
other chemicals used in the U separation process would require at
least another 50 Billion tons of mining/transporting per year.

Those numbers would dwarf the worlds current ore mining and refining
operations by at least fifty(50) fold .

Note: Digging up coal or pumping oil out the ground really doesn't
involve any significant ore separation process.. (Huge difference in
material inputs.)

Repeat as needed. Granted, this takes many thousands of years, but this
is the very long term we're talking about here.

What's the purpose?? We could mine and then refine 20 to 30 million
tons of SiO2, use it to produce/recycle PV, which in turn will
break our dependance on dirty fossil or fission energy sources (and
their supporting infrastructure) for thousands years.- Hide quoted text -

- Show quoted text -

Nice argument. Well supported. But you need to step back and relook at
this.

I think you are going way overboard with an assumption...not in
evidence...that reprocessing/recycling is too expensive. It is not,
otherwise why would they do it? It's *more* expensive, but not that
much more. Nor do yellow cake prices have to be that much higher at
all to make this even more feasable.

ALL fuel can be recycled...and depleted uranium measures in the
hundreds of thousands of tons right now, with remilling can be used
either directly in reactors or, used in MOX fuels, which is become
more popular and is used, or will be used, in most Gen III+ reactors.

This is where breeding comes in as you want the extra Pu to mix with
down grade ore and/or thorium. Most Gen III reactors already do some
breeding...and can easily be configured to bump this up as the
technology slowly matures.

This is why lots of money is going into breeders, or fast-breeders.
But even without breeding, just the use of non-breeding MOX and
various other reactor technologies NOW, with reprocessing, your
gazillion tons of ore is simply way exaggerated. It won't be
necessary.

IF we look to a simple *doubling* of the number of reactors, that is
increasing GW generation by about 130% (since the new reactors are
bigger than the Gen II ones) we would, in a total closed fuel cycle,
only need a few thousand tons of uranium fuel a year, that's it, at
most.

David

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