Jul 22nd 2010

VIABLE nuclear fusion has been only 30 years away since the idea was first mooted in the 1950s. Its latest three-decade incarnation is ITER, a joint effort by the European Union (EU), America, China, India, Japan, Russia and South Korea to construct a prototype reactor on a site in Cadarache, France, by 2018. If all goes to plan, in about 30 years it will be reliably producing more energy than is put in.

The International Thermonuclear Experimental Reactor became plain ITER following public anxiety about anything that has “thermonuclear” next to “experimental” in its name. ITER aims to produce energy by fusing together the nuclei of hydrogen atoms, confined in a magnetic field at high temperatures—a process akin to that which powers the sun.

For all its cosmic ambition, ITER has run into the earthiest of difficulties: spiralling costs. The project was never going to be cheap. Initial projections in 2006 put its price at €10 billion ($13 billion): €5 billion to build and another €5 billion to run and decommission the thing. Since then construction costs alone have tripled.

Producing electricity from controlled nuclear fusion would require overcoming at least four major ob­stacles. The removal of each obstacle would need major scientific breakthroughs before any reasonable expectation might be formed of building a commercial prototype fusion reactor. It should be alarming that at best only the problems concerning the plasma control, described in point one below, might be investigated within the scope of the ITER project. Where and how the others might be dealt with is anyone’s guess.

These are the four barriers:

1. Commercial energy production requires steady state fusion conditions for a deuterium-tritium plasma on a scale comparable to that of today’s standard nuclear fission reactors with outputs of 1 GW (electric) and about 3 GW (thermal) power…

2. The material that surrounds and contains thousands of cubic meters of plasma in a full-scale fusion reactor has to satisfy two requirements. First, it has to survive an extremely high neutron flux with energies of 14 MeV, and second, it has to do this not for a few minutes but for many years…

3. The radioactive decay of even a few grams of tritium creates radiation dangerous to living organ­isms, such that those who work with it must take sophisticated protective measures…

4. Problems related to tritium supply and self-sufficient tritium breeding will be discussed in detail in Section 5.2, but first, it will be useful to describe qualitatively two problems that seem to require simultaneous miracles, if they are to be solved…

Oct 22nd 2009
From The Economist print edition
An alternative approach to achieving nuclear fusion in the laboratory

LIKE conquistadors seeking El Dorado, physicists cannot leave the idea of fusion power alone. Some spend billions of dollars of taxpayers’ money on the huge machines they believe are the best way to generate the temperatures and pressures needed to persuade atomic nuclei to merge with one another. Others still think there is something to the idea of “cold” fusion, and tinker hopefully with desktop apparatus full of electrodes made from exotic metals and electrolytes containing obscure isotopes of hydrogen.

Eric Lerner, however, believes there is a third way. His experimental device does not quite fit on a desktop (its sides are a couple of metres long) but nor does it cost billions (a few hundred thousand is closer to the mark). Nor, in truth, does it do fusion yet. But on October 20th he announced it had reached what might be seen as base camp on the climb to that goal.

Mr Lerner’s machine is called a dense plasma focus fusion device. It works by storing charge in capacitors and then discharging the accumulated electricity rapidly through electrodes bathed in a gas held at low pressure. The electrodes are arranged as a central positively charged anode surrounded by smaller negatively charged cathodes.

When the capacitors are discharged, electrons flow through the gas, knocking the electrons away from the atomic nuclei and thus transforming it into a plasma. By compressing this plasma using electromagnetic forces, Mr Lerner and his colleagues at Lawrenceville Plasma Physics, in New Jersey (the firm he started in order to pursue this research) have created a plasmoid. This is a tiny bubble of plasma that might be made so hot that it could initiate certain sorts of fusion. The nuclei in the plasmoid, so the theory goes, would be moving so fast that when they hit each other they would overcome their mutual electrostatic repulsion and merge. If, of course, they were the right type of nuclei.

“An international plan to build a nuclear fusion reactor is being threatened by rising costs, delays and technical challenges. ‘Emails leaked to the BBC indicate that construction costs for the experimental fusion project called Iter have more than doubled. Some scientists also believe that the technical hurdles to fusion have become more difficult to overcome and that the development of fusion as a commercial power source is still at least 100 years away. At a meeting in Japan on Wednesday, members of the governing Iter council will review the plans and may agree to scale back the project.’ Iter will be a Tokamak device, a successor to the Joint European Torus (JET) in England. Meanwhile, an experiment in fusion by laser doesn’t seem to be running into the same high profile funding problems just yet.”

“The old joke is that fusion is the power of the future and always will be. But it’s not looking so funny for ITER, an EU10 billion fusion experiment in France. According to Nature News, ITER will not conduct energy-producing experiments until at least 2025 — five years later than what had been previously agreed to. The article adds that the reactor will cost even more than the seven parties in the project first thought:’…Construction costs are likely to double from the 5-billion (US$7-billion) estimate provided by the project in 2006, as a result of rises in the price of raw materials, gaps in the original design, and an unanticipated increase in staffing to manage procurement. The cost of ITER’s operations phase, another 5 billion over 20 years, may also rise.”

My feature in the Toronto Star today is about General Fusion, a Vancouver-area startup that believes it can build a prototype of a nuclear fusion reactor for $50 million within four years. While the multibillion-dollar ITER and U.S. fusion programs are using costly lasers and electromagnets to achieve “net gain” — that is, creating a fusion reaction that releases more energy than put it — the folks at General Fusion are cleverly pursuing a mechanical approach that uses concentrated sound waves to compress a deuterium-tritium plasma and trigger a fusion reaction. The key, as you’ll see, is the use of precision digital controls that simply didn’t exist back in the 1970s when the idea of magnetized target fusion was first explored.

The price isn’t right

ITER will cost more to build than previously thought. Now is the time to be honest about how much.

“So it is not a complete surprise that a recently finished design review of ITER, a major fusion experiment to be built in Cadarache, France, is forecasting a delay of 1–3 years in its completion date and a roughly 25–30% increase in its euro dollar5-billion (US$7.8-billion) construction cost”

The money will make up about 10 percent of the cost of the project, which is working to develop the world’s first commercial fusion reactor by 2016. If the ITER developers can perfect fusion technology, then they will make the designs for the commercial reactor available worldwide.

Half of China’s contribution will be spent during the 10-year construction phase of the project located in Cadarache, France, Delong said.

The experimental fusion reactor is also backed by the European Union, India, Japan, Russia and the United States