Re: OT: Global cooling 34 million years ago

On Mar 5, 1:23 am, "Tim Williams" <tmoran...@xxxxxxxxxxx> wrote:
<bill.slo...@xxxxxxxx> wrote in message

news:63e0231f-dfad-4c3c-9844-d2d690166bdf@xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx

Perhaps warmingists know enough physicis to be aware that nuclear
fission produces radioactive nuclear waste, which emits alpha, beta
and gamma rays. An ignorant savage like Rich may not appreciate that
these constitute emissions

Actually, they don't, since they don't emit beyond their container.  

Which rather begs the question of the quality of containment that we
can guarantee over the half-lives of the emitters.

There
are a few exceptions, like krypton and xenon, which are only freed when the
fuel is exposed to atmosphere (such as opening the zirconium-clad fuel
bundles, or especially breaking down the fuel by careless reprocessing), and
the tritium (as tritiated H2 gas, H2O, etc.) that is produced by all
water-based reactors, but CANDU reactors in particular (being heavy-water
moderated).  Levels of both are an order of magnitude below regulatory
standards at currently operational facilities, and those standards are a
further order of magnitude or two below any potential health effects.
Nuclear is indeed a very clean technology today.

As long as it works the way it is supposed to. At Three Mile Island,
human stupidy didn't quite manage to break the container, but
Chernobyl a comparable allowance of stupidity managed to thoroughly
trash a ratehr poorer container. I've got a lot of faith in human
stupidity, particularly when couple with self-confident complacence -
of which there's no shortage around here - and nuclear reactors strike
me as excessively dangerous toys.

Tritium, krypton and xenon aren't a big concern because they spread out
fairly well.  Gaseous, they are quickly diluted by the atmosphere to
negligible levels.  Tritium in the groundwater is a bit more concentrated,
which is why it's monitored.

Probably of a bigger concern is the ~1% of CO2 still produced by nuclear
processing.  This includes (as far as I know) mining, transport, fabrication
and etc.  Considering coal is approximately 100% CO2 per electrical output,
it can be said that nuclear has negligible carbon emissions.

I may be a warmingist, but I don't think that global warming is the
only thing we have to worry about.

but the more sophisticated may understand
that nobody has yet worked out an entirely satisfactory way of
disposing of this waste in a way that can be guaranteed not to foul
the world we leave to our children.

France and Japan seem to have some ideas.  Right now, they both reprocess
their spent fuel; the U.S. doesn't.  The heavy stuff (thorium and up) can be
burned again (MOX fuel), getting rid of those pesky actinides, which are the
main reason spent fuel needs to sit under North America for 10kya by the
current regulatory standards here.  If the byproducts are seperated, it's
safe after just a couple of centuries encased in glass, a much easier
storage time, conceivable even that the government that produced it will see
it become safe again.  And with rhodium as expensive as it is (especially
2003-2006), it's even economical to extract PGMs from the stuff after just
half a century.

Even without reprocessing, nuclear is still safe with low emissions.  Pebble
bed technology isn't very mature, but there's no reason not to use it.
Germany, of all places, even experimented with the stuff, successfully
operating a reactor for a decade or so.  It's hard to reprocess, so it's not
a proliferation threat either.  The pebbles are self-contained and ready for
disposal.

And speaking of disposal, I don't see why we don't just heap all the waste
into a deep hard-rock mine shaft (below the water table) with some sacks of
graphite, heap concrete on top and let it soak.  With a couple thousand tons
of waste in one place, it should get hot enough to melt and sink deeper into
the Earth's crust, never to be seen again for millions of years, in which
time there will be little more than depleted uranium leftover.  With
concrete on top, the byproducts will be fairly well contained, and it's deep
enough that it won't be a big deal for the water table, either.  It's going
to be deep enough, fast enough, that there isn't any concern of future
miners touching the stuff with their drill rigs.  And it's better than
dumping it deep in the ocean where it's still accessible for a few thousand
years.  I don't know, I've never heard this proposed, maybe the water table
doesn't work quite the way I think.  But it sounds good to me, at least if
you're not reprocessing the stuff, which sounds better to me.

http://en.wikipedia.org/wiki/Synroc

One of my undergraduate friends spent most of his working life on this
system of nuclear waste disposal. It seems to offer everything that
anybody could want, but it still hasn't been put to practical use - if
British Nuclear Fuels ever did make any, I've yet to hear about it. I
suppose it still could happen.

http://www.ainse.edu.au/news_repository/aussie_synroc_in_us_technology_deal..html

--
Bill Sloman, Nijmegen
.

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