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Iter Project: energy from Sun-like nuclear reactions

 
 
Reply Tue 21 Nov, 2006 01:39 pm
Quote:
Iter Pact Signed

By Daniel Clery
ScienceNOW Daily News
21 November 2006

A $12-billion worldwide attempt to generate power from nuclear fusion was signed into existence today by ministers from the project's seven international partners--China, the European Union, India, Japan, Korea, Russia, and the United States. The International Thermonuclear Experimental Reactor (ITER) project has been 2 decades in the making, and with today's signing, construction of the reactor in southern France can begin next year.
Nuclear fusion is the process that powers the sun and stars. It happens when atomic nuclei slam together with such force that they fuse together into a larger nucleus, releasing a small portion of the mass of the original nuclei as a tremendous amount of energy. In ITER, the nuclei used will be deuterium and tritium--isotopes of hydrogen--which can be extracted in almost limitless quantities from seawater. Running a fusion reactor creates a small amount of short-lived radioactive waste that decays in a matter of centuries; waste from traditional nuclear reactors usually sticks around for tens of thousands of years.

But fusion is no easy matter: The nuclei must be heated to 100 million degrees, and the resulting ionized gas, or plasma, held in place with huge and powerful superconducting electromagnets to prevent it from touching the sides of the vessel, a doughnut-shaped steel enclosure called a tokamak. It takes a huge amount of energy to get the plasma into this state, and the goal for ITER researchers is to demonstrate that they can control the fusion reaction and generate 10 times as much power as the reactor consumes.

ITER has had a long and difficult history, beginning in the mid-1980s at the suggestion of Russian scientists in part as a way of easing East-West tension. After the engineering design was finished in 1998, governments balked at the cost and instructed researchers to cut the price by 50%. The United States pulled out the following year. Things picked up after a slimmed down design was finished in 2001: China and Korea joined the effort in 2003, and the United States rejoined.

Progress was stalled during 2004 and early 2005 as the partners argued over where to build the reactor, but in June 2005, the parties agreed on Cadarache, France, 60 kilometers from Marseilles (ScienceNOW, 28 June 2005). The European Union will foot 50% of the construction costs, with the other partners (including new member India) splitting the rest equally. ITER is expected to produce its first plasma in 2016 and operate for 20 years.

In a related event, tomorrow will see initial approval of a consolation package for Japan, the loser in the competition to provide a site for ITER. As part of the deal agreed in June 2005, some $870 million will be spent on fusion related facilities in Japan, with equal contributions from Japan and the European Union. The aim is to carry out work that will speed the effort towards a commercial fusion power reactor after ITER. Japan plans to gut its existing JT-60 tokamak and rebuild it with superconducting magnets as a fusion testbed. It will also lead a design effort for a materials testing facility and construct a fusion research center in northern Japan. The need to compensate the runner-up "has turned necessity into advantage for the fusion program," says G√ľnter Janeschitz, head of fusion at Germany's Karlsruhe research center.


http://i10.tinypic.com/48h1d2q.jpg

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Type: Discussion • Score: 1 • Views: 838 • Replies: 7
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stuh505
 
  1  
Reply Tue 21 Nov, 2006 04:49 pm
Although the sun does produce energy through fusion I think it is a bit misleading to call it sun-like, because in the sun it is protons that fuse to form deuterium, and with ITER they are talking about fusing deuterium and tritium to make helium.

Anyway, it's way cool! I hope it works.

It sounds like it would be extremely difficult to do...heating the gas to a plasma and maintaining a temperature in the ten's of millions...even at these temperatures (and proton velocities), it takes an extremely long time for two protons to collide precisely enough to overcome the repulsion of the electric field and get into range of the strong nuclear force

...so if they can pull it off, that would amazing first of all, and even more amazing if they can do it without sublimating a large portion of the Earth in the extreme temperatures.

Global warming, what? Hey, at least the world will finally be united in this effort, even if it does spell the end of mankind in an ironic display of human overconfidence.
0 Replies
 
Setanta
 
  1  
Reply Tue 21 Nov, 2006 04:56 pm
They had an interesting piece on this on CBC this afternoon, which i didn't entirely understand, partly because i wasn't paying close attention.

Thanks for posting this, Walter.
0 Replies
 
Setanta
 
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Reply Tue 21 Nov, 2006 04:57 pm
Oh the sun is a mass
Of incandescent gas
A gigantic nuclear furnace
Where hydrogen is turned into helium
At a temperature of millions of degrees . . .


-- They Might Be Giants
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contrex
 
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Reply Thu 23 Nov, 2006 10:03 am
stuh505 wrote:
Although the sun does produce energy through fusion I think it is a bit misleading to call it sun-like, because in the sun it is protons that fuse to form deuterium, and with ITER they are talking about fusing deuterium and tritium to make helium.


Stuh505, the fusion reaction in the sun is a multistep process in which hydrogen is burned into helium, hydrogen being the "fuel" and helium the "ashes."

The cycle starts with the thermal collision of two protons (1H + 1H) to form a deuteron (2H), with the simultaneous creation of a positron (e+) and a neutrino (v). The positron very quickly encounters a free electron (e-) in the sun and both particles annihilate, their mass energy appearing as two gamma-ray photons. Once the deuteron has been produced, it quickly collides with another proton and forms a 3He nucleus and a gamma ray. Two such 3He nuclei may eventually (within ten thousand years) find each other.

Overall, this amounts to the combination of four protons and two electrons to form an alpha particle (4He), two neutrinos, and six gamma rays.
0 Replies
 
stuh505
 
  1  
Reply Thu 23 Nov, 2006 11:25 am
Contrex: Right, so, like I just said, in the sun it is protons that fuse to form deuterium...
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contrex
 
  1  
Reply Thu 23 Nov, 2006 01:37 pm
stuh505 wrote:
Contrex: Right, so, like I just said, in the sun it is protons that fuse to form deuterium...


But it is too slow to be used here on earth, right?
0 Replies
 
stuh505
 
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Reply Thu 23 Nov, 2006 09:07 pm
Well, at a temperature of 10 million degrees in the sun the protons (hydrogen nuclei) are traveling > 1000 km/s. At this speed it the average proton will rebound for 14 billion years before getting close enough to undergo fusion. But, there are enough protons in the sun that there is still a rate of 100 million collisions per second. Of course, the sun has a diameter of 1.4 million kilometers...whereas this ITER machine uses a human figure standing next to it for scale.

I guess they figure by making the core of the ITER machine 10 times hotter than the core of the sun, they will accelerate the fusion reactions. Also, I would assume it is probably a little easier to do fusion with deuterium and tritium because they would have more momentum.
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