From: dietz@interaccess.com (Paul F. Dietz)
Newsgroups: sci.physics.fusion,sci.physics.accelerators
Subject: Re: Put ITER and NOVA on ice; and all-out-attack on Sonofusion
Date: Wed, 13 Aug 1997 03:55:03 GMT

On 12 Aug 1997 23:51:35 GMT, "Carl Dean" <cdean99@mindspring.com>
wrote:


>Fusion has an advantage in that its radioactivity has a much shorter
>half-life and because of this should not invoke as much fear.  It also
>can't melt down, which is another advantage worth noting.

These claims are subject to dispute.

Halflife:  there can be very long lived activation products
produced in the wall, even with ostensibly low activation materials
like SiC (from 28Si --> 27Al --> 26Al, the last have a halflife
of 7.2e5 years.)  [Vanadium may be better, but is scarce and
somewhat expensive.]

Meltdown: with improperly chosen first wall materials, the time
from loss of cooling (and shutdown of the reaction) to melting
of the first wall (from decay of shortlived activation products)
can be only a few minutes.  Proper design and choice of materials
can avoid this, but then that's true of fission as well.

Fear?  Imagine what Greenpeace is going to do with a machine
that puts a blanket containing a megacurie of tritium next
to magnets storing the energy of a small bomb.  Also imagine
the fear of bondholders in a utility that tried to build
a tokamak, since that residual radioactivity is more than enough
to render the core inaccessible to hands-on maintenance.

	Paul

Newsgroups: sci.space.policy
From: Henry Spencer <henry@zoo.toronto.edu>
Subject: 3He fusion (was Re: After Station? (Outreach II))
Date: Fri, 29 Dec 1995 00:15:18 GMT

>If helium-3 fusion was perfected we would have clean nuclear energy.

Well... not entirely.  A D-3He reactor would still produce some neutrons,
because there are D-D side reactions which can't be entirely suppressed.
The problem *would* be much reduced.
-- 
Look, look, see Windows 95.  Buy, lemmings, buy!   |       Henry Spencer
Pay no attention to that cliff ahead...            |   henry@zoo.toronto.edu

From: bds@hagar.ph.utexas.edu (Bruce Scott)
Newsgroups: sci.energy
Subject: Re: What do Netpeople think about fusion?
Date: 15 Sep 1993 15:45:32 GMT
Message-ID: <277das$e3a@geraldo.cc.utexas.edu>

mvp@netcom.com (Mike Van Pelt) writes:

>Fusion has been "Real Soon Now" for so long that I've given up
>waiting for it.

In this we are still paying for the enthusiasm of people who in the
1950s paid no attention to the emerging science of turbulence, and
thought that the production of an MHD-stable magnetic plasma
confinement device would be sufficient to make fusion. You see, if
thermal and particle transport were really caused solely by
collisional diffusion, we would have been producing fusion for the
last 20 years or so.

Unfortunately, it is not like that. Small fluctuations in density or
temperature cause small electric field fluctuations, since the
electrons (with their smaller mass) tend to run away (along magnetic
field lines) from a compression much faster than the ions. Since the
processes are rather slow, the small electric fields generated by this
incipient separation hold the electrons back so that the electron and
ion densities are held equal up to a small correction. These electric
field fluctuations, however, give rise to small-eddy bulk drifting
*across* the magnetic field lines. Turbulence between these "E cross
B" eddies and the density and temperature fluctuations give rise to a
bulk transport out of the device at a rate which is much larger than
would obtain from collisional diffusion, particularly at high
temperatures.

Nobody even surmised this back in the 1950s when all the boy-wonder
propaganda was generated, and people have regrettably taken to
ass-covering rather than truth-telling. It continues today, when
worries over the ability of industrial materials to withstand the sort
of power loads they are going to get in a reactor are not discussed
outside our community. This is a mistake, in my opinion. But
scientists are not to blame for this, unless they submerge their
careful skepticism and make common cause with the Government
propaganda machine. Unfortunately, most of the encounters of the
general public with scientists are with this second sort, and a very
jaundiced and unjustified opinion of scientists in general on the part
of the general public results. Hence, all these "real soon now"
comments and the (predictable) reaction to them. Unfortunately, when
people like me tell the truth about theoretical confinement study ("I
can identify a physical process which I know is important from
comparisons to experimental observations, but because of the necessary
simplifications it is premature to discuss scaling laws, from this
theoretical model or any other.") we get brushed aside or ignored,
because there are any number of people who will beat their chests
("This code has *everything*." or "That issue is *settled*.") to get
attention and, yes, increased funding.

>Some statements I see here are addressed to specific fusion
>technologies, and are not applicable to others.  For instance,
>comments about the problems of high neutron flux are not applicable
>to aneutronic fusion, like 3He.  (Yes, it's harder to fuse 3He than
>other fuels, but since all products are charged particles, you can
>do direct conversion to electricity.)

This is unlikely. I assume you are discussing the reaction

	He3 + D --> alpha + p + 18.3 MeV

Unfortunately, you will get a number of secondary reactions

	D + D --> He3 + n
	      --> T + p		(50 percent branching ratio)

from which you will get some

	D + T --> alpha + n

with that big, bad 14 MeV neutron. For aneutronic fusion you need

	p + B11 --> 3 alpha

but B11 is exotic fuel and the cross section may be difficult
(unfortunately, the NRP Plasma Formulary does not tabulate it).

>My strongest conviction about fusion is that I am absolutely certain
>that if and when fusion becomes a practical source of cheap, clean,
>abundant energy, All The Usual Suspects are going to be all over it
>with "Fusion Kills" signs, chaining themselves to the gates, and
>locking it up in the courts.  Did you see Paul Erlich's editorial back
>when it looked like Cold Fusion was for real?  He denounced it as
>a disaster for the environment, sight unseen.

I'll worry about this when the time comes. Population-growth-induced
environmental problems will be all over us before fusion power comes
on line. Obviously, all those brilliant statements at last year's IAEA
meeting about how fusion is the hope of all those Third-World masses
who want Western-level energy consumption are pretty laughable.

--
Gruss,
Dr Bruce Scott                             The deadliest bullshit is
Max-Planck-Institut fuer Plasmaphysik       odorless and transparent
bds@hagar.ph.utexas.edu (to 12 Oct)                   -- W Gibson

From: bds@hagar.ph.utexas.edu (Bruce Scott)
Newsgroups: sci.energy
Subject: Re: What do Netpeople think about fusion?
Date: 15 Sep 1993 15:54:44 GMT
Message-ID: <277ds4$ehm@geraldo.cc.utexas.edu>

zowie@daedalus.stanford.edu (Craig "Powderkeg" DeForest) writes:

>Actually, this (the idea that fusion will be a nice, clean energy
>source) is a popular misconception.  The most likely plasma hot-fusion
>scenario is tritium-tritium or at least tritium-deuterium fusion, both
>of which produce scads of neutrons and lots of messy neutron-
>activation products, not to mention that they use tritium, which is a
>pretty hazardous radioisotope (hard to contain, and it *loves* to get
>into people, who are perhaps 1/3 hydrogen by nucleus count).

I think you mean "deuterium-deuterium or at least tritium-deuterium"
here. There is no energy gain from a T + T reaction. Your other
comments are correct, not least because in any credible scenario
(except p + B11, a big maybe) there will always be the reaction

	D + T --> alpha + n

with the 14 MeV neutron, at least as a secondary reaction.

In addition to tritium, some pretty exotic things have to be done to a
plasma containment vessel to keep the plasma at least reasonably free
of impurities (which pick up energy by excitation from collisions with
the electrons and radiate it away), and this involves toxic stuff.
(Whether it is the boron or what is used to apply the boron to the
vessel, I don't know.)

Moreover, we have to come up with a material or combination of
materials out of which to make the "divertor target plates" which have
to take up all the energy which comes out of the plasma. That involves
an industrial process which is probably not too clean, and plenty of
toxic materials.

Of course, other power scenarios have similar problems, but this is
just to counter all those "cheap, clean, limitless" statements.

--
Gruss,
Dr Bruce Scott                             The deadliest bullshit is
Max-Planck-Institut fuer Plasmaphysik       odorless and transparent
bds@hagar.ph.utexas.edu (to 12 Oct)                   -- W Gibson