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The ITER tokamak, with a radius of 9 meters, is the most expensive science experiment in the world after the international space station. It will be built over the next 10 years at Cadarache in southern France (<


ITER Pact Signed

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 away in around a century; high-level waste from traditional nuclear reactors can stick around for 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 Günter Janeschitz, head of fusion at Germany's Karlsruhe research center.

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