NetNews Usenet Archive 1993 #3/NN_1993_3.iso/spool/sci/energy/7245

Internet Message Format | 1993-01-25 | 5.9 KB

Path: sparky!uunet!munnari.oz.au!yoyo.aarnet.edu.au!news.adelaide.edu.au!spam!jaskew
From: [e-mail] (Joseph Askew)
Newsgroups: sci.energy
Subject: Re: True Costs of French
Summary: Who cares about the technical details
Message-ID: <[e-mail]>
Date: 26 Jan 93 00:01:34 GMT
References: <[e-mail]> <[e-mail]> <[e-mail]>
Followup-To: sci.energy
Organization: Statistics, Pure & Applied Mathematics, University of Adelaide
Lines: 93

In article <[e-mail]> [e-mail] writes:
>In a previous article, [e-mail] (David Cameron) wrote:
>>In article <[e-mail]> [e-mail] (Tino) writes:
>>>In article <[e-mail]> [e-mail] (Joseph Askew) writes:

>>>>The SuperPheonix fiasco certainly
>>>>would take a lot of explaining!

>>I for for one would be interested in an explanation at about the tech level
>>of Scientific American [or perhaps one of their sidebar mini-articles]
>>Please expand any abbr [abbreviations] on first use.

Most reactors require a moderator to slow down neutrons from fission events.
This is because the concentration of U235 is very small and U235 has a far
great ability to absorb slow neutrons than U238. If they aren't slowed down
then too many of them are absorbed by the U238 and the reaction grinds to a
halt. In fast breeder reactors the moderator is removed completely. This is
made for by a very high level of fissile material mostly Pu239. This means
there are a great deal of neutrons available, enough so that those absorbed
by the fertile U238 doesn't matter. When a U238 atom absorbs a neutron it
eventually forms a Pu atom (after some decay events not worth mentioning)
Therefore if enough U238 atoms can be turned into Pu239 then the possibility
of producing *more* Pu than you burn is open. (I can't quite remember but
I think a Pu fission produces 3 neutrons only one of which has to hit a
U238 atom for another Pu to be formed and one to hit a Pu atom to continue
the reaction. This leaves a surplus some of which is absorbed by the
cladding or structure but most of which is clear 'profit') There are some
problems with these reactors. Firstly hydrogen is a great moderator because
it is so small atomically so you can't use water as coolant. Also because
of the large numbert of fission events a great deal of heat is produced.
This requires a very good coolant. Gasses have been proposed but not to
my knowledge used. All planned, cancelled or operational FBR's I know of (*)
use Sodium metal. This is capable of removing the heat, it doesn't moderate
much but it does become radioactive (a Beta emitter I think) and of course
it burns in air and reacts violently with water. The water reaction produces
hydrogen which if vented into the air is reasonably safe. Unfortuantely as
the sodium is radioactive it cannot be vented so a secondary loop is required.
This means the primary sodium loop cools the core and heats the secondary
sodium loop which heats the water that turns the turbines. FBR's are rather
efficient, 40-45%, in line with modern fossil fuel plants and better than
thermal reactors (30-35%). The three French FBR's all had hydrogen leaks
but not enough to warrent cancellation.

(*) I'm ignoring molten salts and liquid cores as I don't care to explain them.

>The French, perhaps more than any other nation also were deeply
>influenced in their energy policy by the arab oil embargo, and embarked
>on a policy of energy self sufficiency which led to their large nuclear
>electricity generation program.

The French also don't have any large supplies of domestic coal like
Germany and Britain do. I think this played a larger role in the
decision to go nuclear than any other. Look at the countries that are
still developing Fast Breeders. Apart from those with weapons programs
(eg India) it is places without indigenous fuel supplies. Well mostly
only Japan nowadays.

>The French policy towards fast breeders was quite appropriate at the time
>it was conceived, and it is rather unthoughtful to call it a fiasco using
>tha benefit of hindsight.  If all industrialized countries had pushed nuclear
>with the same vigour and general success as the French, their move towards
>fast breeders would have been seen as far-sighted and correct.

When I described the SuperPhoenix mess as a fiasco I wasn't referring to
the technical problems which I have always thought were relatively minor.
It was the whole concept and planning. Sure if the French had got it to
work I would be the first to congratulate them, but as they have this
thing with secrecy, no desire to consult with local communities, no regard
for pressure groups whether respectable or otherwise (local residents and
Greenpeace respectively) and so on trouble was inevitable. If the French
government was more open then people would trust them more. They left the
public relation field open to Greenpeace because of their arrogance. If
the French government and EdF had stuck their noses out of their comfie
offices in Paris they might have been able to sell the whole concept. In
short what is wrong with the French is exactly what some people around
this group claim is right (ie not listening to people and tear gassing
protestors). It doesn't require hindsight to see that you cannot treat
peoples objections with scorn and derision for long without landing in
trouble.

>It is true that the SuperPheonix has had some technical problems, but it is
>not obvious that they could not be overcome in that reactor or successors,
>if there were still the same drive and commitment to the concept.

Absolutely true!

Joseph Askew

--
Joseph Askew, Gauche and Proud  Barbarian horns draw out the northern wind;
[e-mail]  Paler than water lies the Thistle Pass;
Disclaimer? Sue, see if I care  Sky swallows up the road to Kokonor;
One China One Korea One Eire32  Moonlight, a thousand miles along the Wall.