Thorium: the future of nuclear power?

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Thorium: the future of nuclear power?




by Christophe » 16/02/14, 14:14

Abundant resource with high energy potential, lower quantity and dangerousness of waste: thorium could support the development of a new nuclear industry, but this mineral seen by its supporters as nuclear "green" is not necessarily a miracle solution.

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"Thorium is three to four times more abundant in the earth's crust than uranium, especially in countries that are likely to build reactors in the future, such as India, Brazil, and Turkey," Martha Crawford explains. -Heitzmann, director of research, development and innovation of the French nuclear giant Areva.

"If new reactors are built, these countries could ask us for solutions to thorium," she adds.

Areva signed with the Belgian Solvay, in December, an agreement including a research and development program to study the exploitation of this mineral as a potential fuel for nuclear power plants.

Experimental thorium reactors had been built as early as the middle of the 1950 years, but the researches put in parentheses in favor of uranium.

"They were motivated by the fear of a shortage of uranium. Then they slowed down, particularly in France, where the uranium cycle was closed by setting up a spent fuel recycling system, "says Crawford-Heitzmann.

If the research resumes today, it is because the abundance of the resource would benefit some countries, like India which, with about a third of the world's reserves, is clearly engaged in the thorium way in the part of its ambitious civilian nuclear development program.

On the other hand, no upheaval in sight in a nucleusized France. "Many countries have invested billions and billions of euros in industrial infrastructure that depends on uranium. They seek to amortize them and do not want to replace them, "says Crawford-Heitzmann.

The benefits are not decisive enough to take the plunge. "The interest of thorium only makes sense in highly innovative reactors, such as those with molten salts, which are still paper-based," according to CNRS project manager Sylvain David, who is working on such a project in Paris. the Institute of Nuclear Physics at Orsay.

Evolution rather than revolution

Main disadvantage of thorium: it is not naturally fissile, unlike uranium 235 used in the current reactors. It is only after absorption of a neutron that it produces a fissile material, uranium 233, necessary to trigger the chain reaction in the reactor. To start a thorium cycle, you need uranium or plutonium (from plant activity).

"Not to mention that it will take several decades to accumulate enough fissile material to start a cycle," says the Commission for Atomic Energy (CEA).

The risks are not zero either. Certainly, thorium fuels melt at a higher temperature, delaying the risk of melting the reactor core in the event of an accident. "But we can not say that it is the magic cycle where there is no more waste, more risks, more Fukushima", insists Mr. David.

233 uranium is highly irradiating, which would require "much more complicated factories, with shielding to respect the rules of radioprotection", according to the CEA.

As to say that the waste is less radioactive, "it is not correct: the radioactivity is lower at certain periods, and stronger at others. There is not an absolutely decisive advantage in this respect.

Result: the industrial production of energy through thorium is not for tomorrow.

"I do not think we'll have any reactors before 20 or 30. And this will be done gradually, in addition to the closed cycle, "predicts Martha Crawford-Heitzmann. Especially since with the closed uranium-plutonium cycle, "the nuclear resource is ensured for centuries".

With this in mind, the CEA is developing a prototype for a sodium-cooled fast neutron reactor, called "Astrid", which, thanks to uranium 238, makes it possible to use the plutonium several times and even to produce more than it does. consumes by "breeding".

However, uranium 238 represents 99,3% of uranium ore and "large quantities have already been extracted from mines, which we do not know what to do," says David.


http://www.20minutes.fr/planete/1300034 ... aire-futur
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by sen-no-sen » 16/02/14, 14:36

This is not new, the development of 4 generation reactors thorium is expected for a long time, it lacks only an energy crisis and the choice will be quickly taken ...
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by Cuicui » 16/02/14, 15:16

sen-no-sen wrote:This is not new, the development of 4 generation reactors thorium is expected for a long time, it lacks only an energy crisis and the choice will be quickly taken ...
Why not hydrogen-boron fusion? No waste, very little radiation, abundant fuel, rustic technology.
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by sen-no-sen » 16/02/14, 15:44

Cuicui wrote:
sen-no-sen wrote:This is not new, the development of 4 generation reactors thorium is expected for a long time, it lacks only an energy crisis and the choice will be quickly taken ...
Why not hydrogen-boron fusion? No waste, very little radiation, abundant fuel, rustic technology.


Simply because this technology is not yet mature enough!
But it is actually planned that in the long term the fusion replaces the fission.

A small diagram
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ITER to lead in the wing but certainly that competing projects will give results over the centuries (ZR machines?)
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Thorium and RSF




by RégsB » 26/04/14, 14:03

Hello,

I have been interested for a few days in Thorium. The associated technology of Melt Salt Reactors seems to me to be a great step forward compared to the current technique and even to the next one (EPR).
Among the advantages I retain: these RSFs are so stable that there is no need for an evacuation plan. Some could even be designed to consume a large part of the "hot" waste of current power plants.
I find it not bad at all!
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by Philippe Schutt » 26/04/14, 20:10

From memory, SuperPhenix used molten sodium and was shut down due to repeated leaks in this circuit. Finally, following the pressure of public opinion due to these breakdowns.
These leakage problems were apparently solved the last year, and the know-how acquired.

However, reviving this sector of sodium heat transfer fluid seems doubtful, given the characteristics of this product. At least it should be nonflammable!
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by RégsB » 26/04/14, 21:38

Hi,

Exactly, these RSFs do not use liquid sodium which explodes in contact with air or water, but fluorine which is without these disadvantages and moreover at a standard atmospheric pressure.
Hence a mastery much easier than for the ASTRID project studied by the CEA and AREVA at this time.
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by Philippe Schutt » 27/04/14, 09:13

ah? I'm not up to date then ...
I must see what compound they used, because pure fluorine is rather worse.
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by RégsB » 27/04/14, 09:52

Hi,

From what I read, the fluoride salt is boiling (about 700 ° C) in the reactor core. An accident like the melting of the reactor if cooling failure can not happen : Mrgreen:
If there is a breakdown or emptying of the heart, it is done by gravity by letting a frozen salt plug by a cooler melt. The flow is done in several tanks which make the continuation of the reaction impossible. There, the liquid cools quietly by itself solidifying.

A good site on the subject:

http://energieduthorium.fr/
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by sen-no-sen » 27/04/14, 11:11

RégsB wrote:Hi,

From what I read, the fluoride salt is boiling (about 700 ° C) in the reactor core. An accident like the melting of the reactor if cooling failure can not happen : Mrgreen:
If there is a breakdown or emptying of the heart, it is done by gravity by letting a frozen salt plug by a cooler melt. The flow is done in several tanks which make the continuation of the reaction impossible. There, the liquid cools quietly by itself solidifying.

A good site on the subject:

http://energieduthorium.fr/



There is also technology PBMR or modular reactor with a bed of balls.

The traditional uranium bar is replaced here by graphite balls containing radioactive fuel, the heat transfer fluid being an inert gas of the helium or nitrogen type, this removes the risk of melting of the reactor core as much as possible.
THTR technology has been around since the 80 years, and is currently being retested at MIT.
But that does not change the thorny problem of waste!
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