On Sat, Sep 15 meekerdb <meeke...@verizon.net> wrote:

> in the present case there is no mystery about where the CO2 comes from
> and whether it's a natural cycle - it's us.
>

Probably, but I'm not terribly concerned about it, the increase in CO2 over
the last century is really just a blip; in fact at NO time in the last 600
million years has CO2 levels been significantly lower than now and during
most of that time it was about 10 times higher than now, sometimes closer
to 15 or even 20. And yet life thrived. And I think people sometimes forget
that CO2 is not the most important greenhouse gas, water vapor is.

> I'm giving a talk Monday on why we should be building molten-salt thorium
> reactors to replace the burning of fossil fuels for electrical power.
>

Excellent! I think Liquid Fluoride Thorium Reactors are the best hope for
replacing fossil fuels which will run out eventually. Consider the
advantages:

*Thorium is much more common than Uranium, almost twice as common as Tin.
And Thorium is easier to extract from its ore than Uranium. It would only
take 2000 tons of Thorium to equal the energy in 6 billion tons of coal
that the world uses each year. There is 120 TRILLION tons of Thorium in the
earth's crust and if the world needs 10 times as much energy as we get from
just coal then we will run out of Thorium in the crust of this planet in 6
billion years

* A Thorium reactor burns up all the Thorium in it; A conventional light
water reactor only burns .7% of the Uranium in it, the U235.

* To burn the remaining 99.3% of Uranium, the U238, you'd have to use a
exotic fast neutron breeder reactor, Thorium reactors use slow neutrons and
so are inherently more stable because you have much more time to react if
something goes wrong. Also breeders produce massive amounts of Plutonium
which is a bad thing if you're worried about people making bombs. Thorium
reactors produce an insignificant amount of Plutonium.

* Thorium reactors do produce Uranium 233 and theoretically you could make
a bomb out of that, but it would be contaminated with Uranium 232 which is
a powerful gamma ray emitter which would make it suicidal to work with
unless extraordinary precautions were taken, and even then the unexploded
bomb would be so radioactive it would give away its presents if you tried
to hide it, destroy its electronic firing circuits and degrade its chemical
explosives. For these reasons even after 65 years nobody has a Uranium 233
bomb in its stockpile.

*A Thorium reactor only produces about 1% as much waste as a conventional
reactor and the stuff it does make is not as nasty, after about 5 years 87%
of it would be safe and the remaining 13% in 300 years; a conventional
reactor would take 100,000 years.

*A Thorium reactor has an inherent safety feature, the fuel is in liquid
form (Thorium dissolved in un-corrosive molten Fluoride salts) so if for
whatever reason things get too hot the liquid expands and so the fuel gets
less dense and the reaction slows down.

*There is yet another fail safe device. At the bottom of the reactor is
something called a "freeze plug", fans blow on it to freeze it solid, if
things get too hot the plug melts and the liquid drains out into a holding
tank and the reaction stops; also if all electronic controls die due to a
loss of electrical power the fans will stop the plug will melt and the
reaction will stop.

*Thorium reactors work at much higher temperatures than conventional
reactors so you have better energy efficiency; in fact they are so hot the
waste heat could be used to desalinate sea water or generate hydrogen fuel
from water.

* Although the liquid Fluoride salt is very hot it is not under pressure so
that makes the plumbing of the thing much easier, and even if you did get a
leak it would not be the utter disaster it would be in a conventional
reactor; that is also why the containment building in common light water
reactors need to be so much larger than the reactor itself. With Thorium
nothing is under pressure and there is no danger of a disastrous phase
change so the expensive containment building can be made much more compact.

  John K Clark

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