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The power of fusion

A project involving 34 nations will produce electricity via nuclear fusion

Devangshu Datta  |  New Delhi 

Devangshu Datta

One of the many positive outcomes of the end of the Cold War has been greater willingness on the part of governments to cooperate in fundamental research. The $9 billion Large Hadron Collider (LHC) was a shining example of multinational scientific cooperation.

An even larger multinational project is on the anvil. The International Thermonuclear Experimental Reactor (ITER) was actually mooted in 1985 during the Gorbachov-Reagan era, when the US and the former USSR agreed to collaborate on nuclear fusion research. But despite the European Union, South Korea, Japan, China and Indian signing on at various stages, the project didn't make much headway until recently when interest in it was renewed.

The ITER agreement was formally signed only in 2006. Unlike the LHC, the ITER project aims for the proof of concept of research, which has direct technological applications. The 34-nation, $13 billion project is intended to develop ways to control nuclear fusion in order to generate electrical power. The coordination is so complex that ITER uses its own virtual currency unit - the Iter unit of account - to compute the value of contributions by partner nations.

Nuclear fusion - the joining of atoms of one element to create another element - is the energy source that drives stars. In the simplest fusion reactions, hydrogen nuclei combine to form helium, while converting excess particles into energy. Fusion is clean, with high energy output and no radioactive waste products. Since fusion is fuelled by hydrogen, which is the most abundant element in the universe, it is also, in theory, a nearly-inexhaustible energy source. It is also safe in another sense - if something goes wrong, fusion simply doesn't happen.

In these respects, fusion contrasts favourably with nuclear fission, the nuclear reaction where atoms are split, with energy being released along with the creation of toxic radioactive elements. Disasters like Fukushima, Chernobyl and Three Mile Island have highlighted the dangers of fission.

Unfortunately, unlike fission reactions that can be easily controlled to generate electricity, fusion is an explosive reaction that isn't easy to control. Controlled fusion would be the perfect answer to the world's energy needs since it would offer clean, inexhaustible energy without the environmental issues of fossil fuels, or the risks of fission gone wrong, or the need to dispose of radioactive waste.

Fusion requires conditions of immense heat and pressure as is found inside stars. One of the ways to create those conditions is to explode a fission device (an "atom bomb"). The bomb generates the heat and pressure required to start a fusion reaction, thereby triggering off a "hydrogen bomb", more correctly described as a thermonuclear device.

Another way to create fusion conditions is by using a device called a Tokamak. Tokamak is a Russian acronym for a doughnut-shaped ("toroidal") chamber with magnetic fields. It was invented sometime in the 1950s by a team of Soviet researchers, led by Andrei Sakharov and Igor Tamm. The Tokamak chamber contains plasma, super-heated, electrically conductive gas. The plasma is squeezed inside the chamber by using magnetic fields.

While Tokamaks work in the sense that they can produce fusion under more or less controlled conditions, the input energy required to super-heat the plasma and run the magnetic fields is more than the energy output from the fusion. More than 200 Tokamaks are known to be in operation in various research projects. The smallest one is the size of a compact disc, while the largest is that of a five-storey building.

ITER aims to build a massive Tokamak, 10 times the volume of anything in operation and weighing around 23,000 tonnes. The ITER Tokamak will produce temperatures of well over 100 million Celsius - many times hotter than the centre of the sun.

It is supposed to have a net surplus power output. The building site, which is about the size of 60 soccer fields, is in Cadarache, in southern France, close to the headquarters of the French atomic research agency. The components will be fabricated in various places and assembled on-site. India will contribute some of the million-odd parts of the Tokamak. France has just issued ITER the necessary licences to run a nuclear plant.

Using the machine, scientists will be able to study plasma under conditions similar to that required in a power plant. ITER will not only be the first fusion experiment to produce net power; it will also test all the key technologies, including heating, control, diagnostics, and remote maintenance.

The target is to develop ways and means of generating net 500 Mw of fusion power using input power of 50 Mw. That positive input-output ratio, or positive "Q" as it's known, would be the first sign that controlled fusion is a viable energy source. However, the ITER Tokamak will produce its energy as heat rather than electricity. Methods will have to be found to efficiently convert that heat into useful power.

The project timeline is epic, running over several decades. The Tokamak assembly is due to start in 2015 and it will start operating somewhere between 2020-22. The first plasma experiments should be in process by 2022. ITER will first use hydrogen plasma, and then switch to experiments with hydrogen isotopes like tritium and deuterium mixes.

If all goes well, mixed plasma should be going full-tilt by 2027. Side by side, as data is generated and engineering problems solved, a demonstration fusion power plant will be designed to convert the output. There will be complementary research into fusion materials in other places, with Japan being a key centre. By 2030 or so, ITER hopes to demonstrate fusion power. By 2040, it could be a mainstream component of grid power.

First Published: Thu, May 02 2013. 21:46 IST