France gets nuclear fusion plant

[midnight armadillo]

http://news.bbc.co.uk/2/hi/science/nature/4629239.stm

France will get to host the project to build a 10bn-euro (¡×6.6bn) nuclear fusion reactor, in the face of strong competition from Japan.

The International Thermonuclear Experimental Reactor (Iter) will be the most expensive joint scientific project after the International Space Station.

The Iter programme was held up for over 18 months as parties tried to broker a deal between the two rivals.

Nuclear fusion taps energy from reactions like those that heat the Sun.

Nuclear fusion is seen as a cleaner approach to power production than nuclear fission and fossil fuels.

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This was in the LBN forum, but I thought I'd repost it here since this forum discusses things in a different light, you know? :-) This reqctor is intended to produce sustained fusion reactions as a precursor to a commercial prototype.

[phantom power]

1. Oh, thank god they finally quit arguing about this.

I wonder if recent events regarding oil shortages and climate change lit a fire under their ass.

[Massacure]

2. Don't know about the fire.

But Japan probably got a good deal for letting France host the reactor.

[rfkrfk]

3. if fusion does not work, the earth is toast

I am happy to see that this dispute has been settled.
Nice to see the US involved.

[NNadir]

4. Fusion power depends on fission power.

The correct statement is "without fission power, the earth is toast."

Tritium breeding is impossible. All proposed fusion reactors depend on access to tritium, all of which is obtained in good old fashioned fission reactors.

Most of the world's tritium is available as a by product of the operation of CANDU reactors. The world supply after running these reactors for decades is roughly 25 kg. This is enough to fuel a 1000 MWe fusion reactor for about 3 to 6 months.

It is possible to make tritium via neutron bombardment of Lithium in the core of a fission nuclear reactor. This is no doubt how the internation consortium intends to fuel their fission reactor.

Each fusion reaction releases one neutron. The reaction is D + T -> He-4 + n. In theory one neutron is sufficient to maintain equilibrium (although not breeding). However in reality the neutron capture spectrum for deuterium is extraordinarily low across the entire energy spectrum and the n, Li-6 reaction which gives tritium and He-4 is complicated by the presence of Li-4. In practice too, as all nuclear engineers know, neutrons leak, or are absorbed by structural materials.

Fusion power is just fancy nuclear power.

[phantom power]

5. Beneficial, as a sort of nuclear co-generation?

Thermal co-generation captures waste-heat to extract additional useful energy. Here, we capture waste neutrons (in this case as tritium), to extract additional energy.

[NNadir]

6. Heat exchange is a big problem for fusion reactors.

The question so far as I'm aware has yet to be addressed.

The neutrons from fusion reactions are very high energy, more than 10 MeV, as compared to 1 to 2 MeV from fission reactors (before they are thermalized). It is easy to imagine that as such, fusion neutrons will prove very useful indeed. Many nuclear reactions such as (n,2n) reactions may be possible with neutrons this fast.

Most of the energy released in fusion reactions is, however, in the form of gamma radiation. Gamma radiation is very difficult to convert to heat with high efficiency, since it is so penetrating.

Fusion may prove (in the very long term) a viable way of extending fission resources, but I'm not so sure that fission resources have many limits. I used to believe that this was the case, but recent readings have lead me to suspect otherwise.

The Japanese demonstrated that recovery of uranium from seawater is economically viable if the price of uranium rises to $200/kg. Although the industrial price of uranium is now very low in comparison today, it may someday rise to this level, at which uranium resources may become essentially unlimited.

New uranium is washed to the sea every day by the weathering of granite, so the elimination of uranium from the ocean may not be possible.

It is probably true that the same case applies to thorium. Most of the world's thorium, obtained as a side product from the production of lanthanides from monzanite sands, is now thrown away.

[phantom power]

7. I believe that this new ITER reactor is being built to...

study the practicalities of extracting useful heat from the reactor. Among other things. On their website, they appear to have specific designs in mind for that, but I don't know how much has been tested before, if any.

At any rate, their stated goal is to make this reactor actually produce electricity, on the grid. Not a hell of a lot, but they want to really have a working system, and build larger ones later once they think they've learned enough.

I'll say this, it looks nothing like the gadget that Doc-Oc built in Spider-Man. And nobody was wearing tentacles. Not even in the artist's conceptions.

[NNadir]

8. If this is the website to which you refer...

http://www.iter.org/index.htm

I don't see a heat exchanger or a generator. I'm not saying there isn't one, I just don't see it.

I also don't see where the tritium is coming from.

I note that anti-nuclear anti-environmental activists have already started in complaining that the reactor is on an earthquake fault. They must really, really, really scared of radioactivity since it's quite obvious that this reactor will not operate at all if it's power is shut off.

In the very worst case, the tiny amounts of tritium in the reactor contains might escape and float up to the stratosphere where it will basically have zero environmental impact. I'm sure that weak minded scientifically illiterate anti-environmental anti-nuclear activists would confuse a breach of this reactor's structure with Chernobyl, since their knowledge of science is so very weak.

Whatever. I don't really think fusion power will be of much use for a very long time. It's sort of like PV solar electricity: it generates far more noise than power. It sounds great but basically, it doesn't work yet and may not work for many decades to come.

[phantom power]

9. Here is a gallery of components, which includes some "blanket modules'

My extensive research (fooling around the site a couple years ago) led me to believe that these "blanket modules" are their idea for neutron absorbtion and heat exchange.

At any rate, they mention a "cooling scheme", and if my freshman thermodynamics was worth anything, any cooling scheme represents a way to transport heat away from the reactor, to somewhere else, which means it could be used to run a generator.

http://www.iter.org/gallery-design.htm

They subcontracted the tritium-supply to this guy:

[phantom power]

10. According to another poster (in Science forum)...

They plan to breed tritium from lithium:

http://www.democraticunderground.com/discuss/duboard.php?az=show_mesg&forum=228&topic_id=7528&mesg_id=7555