[ExI] Written for another list

[Eugen Leitl]

On Sat, Aug 04, 2012 at 01:49:39PM -0400, John Clark wrote:

> You always need U-235 or some other neutron source to get the ball rolling
> to produce some initial U-233 for ANY Thorium reactor, but after that it's
> no longer necessary and its on its own.

Of course, that's the theory. In practice you're looking at breeding
factor issues, and bootstrap issues, which clamp down on your growth
kinetics, and hence scaling over time.
 
The large stockpile of Pu-239 is actually your best chance to bootstrap.
Good riddance to bad rubbish.
 
> > Again, the only interesting part of LFTR *concept* is in that it's a
> > molten salt fast or slow breeder based
> > on the thorium fuel cycle.
> 
> 
> LFTR is different from all other fission reactors in 2 ways:
> 
> 1) It uses Thorium as fuel.
> 2) It uses a liquid not a solid fuel.

Yes, I'm quite aware.
 
> > Because we know that uranium cycle fast breeders are impractical.
> >
> 
> I too think Uranium breeders suck.

Didn't expect to hear that from you, but we're distinctly on the same page here.
 
> 
> > > The *concept* has never been validated in all aspects of practical
> > operation
> 
> 
> True nobody has yet made a operational LFTR power plant yet, maybe because
> after a very promising start with a reactor that produced millions of watts
> of power nobody has spent a nickle on the idea in nearly 45 years.

Not quite. The Germans did have the THTR, but apart from being not a breeder
it had too many problems, so they killed it. Canada and India (and a few lesser
countries) are still working on the thorium fuel cycle, so zero budget doesn't 
quite fit.

> Meanwhile tens of billions of dollars have been spent on fusion reactors
> and even today they have yet to output one more watt of power than they
> input. Something is badly out of balance.

I agree! Fusion, particularly Tokamak fusion is making fast breeder
power look like a bargain, by a factor of 100 at least. Throwing good
money after bad on ITER is not very sane. I reserve some judgement on
inertial confinement/laser ignition, but it's probably not going to
work out either (fusion must be a fertile breeder, too).
 
> > we have dozens of *proven* solutions which need to be rolled out on a
> > very wide scale
> 
> 
> Proven?  You can't be talking about wind power or tidal power or solar or
> bio-fuel or geothermal or fusion or power satellites. So what are you
> talking about?

Synfuels, nitrogen fixation at mild conditions, low-temperature
long-lived fuel cells from abundant materials.
 
> > which unfortunately have no vocal supporters.
> 
> 
> They have lots of very vocal supporters in Washington, they're called
> "lobbyist". Nobody would dream of building a wind farm if the government
> didn't bribe companies to do so because it's just not practical otherwise.

You'll see that at least China is converting their coal to synfuels,
with the option to drive the facilities from renewable power and hydrogen
from water electrolysis later.
 
> > Nor absolutely vital parts of R&Dthat absolutely, positively need to be
> > done, now on an emergency schedule (because they were not done in the last
> > 40 years
> >
> 
> What are you talking about?? In the last 40 years billions of dollars of
> R&D money have been spent on all the "green and renewable" energy sources I
> mentioned above (except power satellites), and none of them amount to a
> bucket of warm spit, meanwhile the amount spent on LFTR research is zero.

If I had to spend money now, I would look at nitrogen fixation at
close to RT conditions and methanol synthesis and methane synthesis
and methane fuel cells. As well as MWh scale electrochemical storage
based on cheap and abundant chemistries, like sodium, potassium,
magnesium, molten salt, sulfur, etc.

You'll find that not much money has been spent on above so far,
and right now few people are working on it, and that not a lot
of talent in that area are at all available. This is not a happy
combination.
 
> > This is the part that makes me stock up on popcorn.
> >
> 
> Yes, we may live in interesting times because 7 billion large mammals
> called human beings want to have a a good standard of living and they can't

The 100 TW figures is based on US-level consumption, which might appear
silly, until you factor in that you'll need to compensate for ecosystem
degradation, which needs a lot of energy to be thrown at to compensate
for. So I would actually use 100 TW by 2050 as a ballpart figure to aim
form.

> do that from the energy produced by moonbeams and hummingbirds despite the
> insistence of environmentalists. This is serious business because if they
> can't live well a sizable portion of that 7 billion are going to get mad.

First mad, then dead.

> So you shouldn't automatically reject a possible solution just because it
> has the word "nuclear" in it.

You will find me amazingly open-minded. Also, extremely realist.
 
> > You're a strange man, John.
> >
> 
> I've been told that before.

It can be a compliment.