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ITER Moving Ahead with Fusion Research November 22, 2006

Posted by federalist in Energy.

Exciting news for fusion fans: Yesterday saw formal state commitments to the ITER project.

Factoid: Today’s American per capita energy consumption for an entire year could be serviced by a fusion reactor fueled only by the deuterium in half a gallon of water and the lithium in a watch battery.  Or by over 1000 tons of coal burned in a conventional power plant.  [See Ikeda link at end.]

The ITER plans presently anticipate that commercialized fusion technology is 40 years away.  Their project begins with building a $5BB research reactor in France, and should lead to a prototype fusion reactor after 30 years and another $5BB (current dollars).  Unfortunately, this is a multinational government collaboration, so it will be interesting to see how this actually plays out….

The ITER press kit is an interesting read. 

The aim of ITER is to show fusion could be used to generate electrical power, and to gain the necessary data to design and operate the first electricity-producing plant.

In ITER, scientists will study plasmas in conditions similar to those expected in a electricity-generating fusion power plant. It will generate 500 MW of fusion power for extended periods of time, ten times more then the energy input needed to keep the plasma at the right temperature. It will therefore be the first fusion experiment to produce net power. It will also test all the key technologies, including the heating, control, diagnostic and remote maintenance that will be needed for a real fusion power station.

ITER is a tokamak, in which strong magnetic fields confine a torus-shaped fusion plasma. The device´s main aim is to demonstrate prolonged fusion power production in a deuterium-tritium plasma. Compared with current conceptual designs for future fusion power plants, ITER will include most of the necessary technology, but will be of slightly smaller dimensions and will operate at about one-sixth of the power output level, and will not generate electricity.

The programmatic goal of ITER is “to demonstrate the scientific and technological feasibility of fusion power for peaceful purposes”. After extensive discussions with the scientific community at large, this general goal is now interpreted into a number of specific technical goals, all concerned with developing a viable fusion power reactor.

First of all, ITER should produce more power than it consumes. This is expressed in the value of Q, which represents the amount of thermal energy that is generated by the fusion reactions, divided by the amount of external heating. A value of Q smaller than 1 means that more power is needed to heat the plasma than is generated by fusion. JET, presently the largest tokamak in the world, has reached Q=0.65, near the point of “break even” (Q=1). ITER has to be able to produce Q=10, or Q larger then 5 when pulses are stretched towards a steady state. This is done so that, in the “burning plasma”, most of the plasma heating comes from the fusion reactions themselves, and so that the plant efficiency can be sufficiently high to have a chance of leading to an economically viable power plant.

Secondly, ITER should implement and test the key technologies and processes needed for future fusion power plants – including superconducting magnets, components able to withstand high heat loads, and remote handling.

Lastly, ITER should test and develop concepts for breeding tritium from lithium-containing materials inside thermally efficient high temperature blankets surrounding the plasma. Tritium self-sufficiency of a fusion power plant is a necessary prerequisite, as tritium is not available in nature.

And, a note on safety for all the hysterical technophobes out there:

There is very little fuel in the reaction chamber at any given moment (about 1g in a volume of 1000 m3) and if the fuel supply is interrupted, the reactions only continue for a few seconds. Any malfunction of the device would cause the reactor to cool and the reactions would stop.

The basic fuels – deuterium and lithium – and the reaction product – helium – are not radioactive.

The intermediate fuel – tritium – is radioactive and decays relatively quickly, producing a very low energy electron (Beta radiation).

Kaname Ikeda, Iter Director-General, justifies the project in a short essay here.

One criticism levelled at fusion research is that it will not provide an energy source soon enough and that far too much money is being poured into a long-term gamble.

To put the cost into context, the current world energy market is about three trillion US dollars a year and growing. An energy source that can make an impact on that market, even at a few percent, has an annual market of tens of billions of dollars, several times the lifetime cost of the Iter experiment.



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