Clive Cookson wants the $10bn Iter project to get going without further delay

Iter, the International Thermonuclear Experimental Reactor, has found a home at last.

The six partners in the $10bn project, the world’s costliest scientific facility after the International Space Station, chose Cadarache in southern France at the end of June, after Japan withdrew the rival candidature of Rokkasho in exchange for a generous compensation package.

Iter is the next step toward taming nuclear fusion – the reaction that powers the sun and the hydrogen bomb – to provide a clean and almost inexhaustible energy source for the second half of this century.

Political tussles

The Franco-Japanese wrangle over Iter’s location had caused a delay of more 18 months – and it was just the latest in a long series of technical, political and financial disagreements that have held up the project since a global experiment to demonstrate fusion power was first proposed around 1985.

The US, Russia, Japan, Canada and the European Union began conceptual design work on the doughnut-shaped reactor in the mid 1980s and signed a formal collaborative agreement in 1992. At that point they were talking about starting construction in 1998 and finishing Iter in 2005.

In fact indecision – and a lack of political urgency – have already condemned the project to an overall delay of a decade. The US did not help matters by withdrawing from Iter in 1998 and rejoining in 2003. Canada has pulled out but China and South Korea have come into the partnership.

There is some justice in the complaint by fusion researchers that the low priority given to their field by politicians is the main reason why commercial fusion power always seems to lie 50 years in the future.

New timetable...

The related issues of energy security and global warming (emphasised by the US and Europe respectively) have finally given Iter a push toward reality. The most optimistic timetable now would see construction begin at Cadarache at the beginning of 2007. The reactor would operate for about 20 years from 2015. It aims to produce up to 500MW of fusion power – but in bursts rather than the continuous output suitable for supply to an electric grid.

If all goes well with Iter, a follow-on reactor known as Demo will demonstrate that fusion can reliably run a power station. As part of their price for backing down over Iter, the far-sighted Japanese have won a commitment from the EU to support a Japanese site for Demo, which would begin its design phase in 2020 and operate from 2035, paving the way to commercial fusion plants from 2050.

...if all goes well

Even now, however, the Iter schedule could run into political and financial obstacles.  The partner governments may find it difficult to raise the money they have promised for Iter’s $5bn construction phase. The EU should have no problem providing its half share as host – in fact much of this will come from France – and Japan’s 10 per cent seems secure. But the other four 10 per cent contributions, from the US, Russia, China and Korea, are less sure. China and Korea in particular seem unhappy about the hosting agreement, which will see Japan playing a bigger role in Iter than them without making a correspondingly larger financial commitment.

Then comes the technical challenge of confining the fuel - hydrogen isotopes - as a ‘burning plasma’ at temperatures higher than the centre of the sun, letting the atomic nuclei fuse together to release prodigious amounts of energy. The tokamak reactor, derived originally from a Russian design, holds the electrically charged plasma in place with superconducting magnets. An inherent safety feature of fusion power is that the slightest disturbance immediately cools the plasma and stops the nuclear reaction.

There is no doubting the basic physics of fusion, and experience with smaller-scale experimental reactors such as Europe’s Jet at Culham near Oxford suggests that the process can be scaled up to provide a clean and virtually inexhaustible power source.

Antinuclear campaigners condemn Iter as a waste of money. However, even if Iter runs well over budget, its spending level is unlikely to exceed $1bn a year. That would be a small price to pay for even a 20 per cent chance of giving the world another energy option for a time when it will certainly no longer be possible to burn fossil fuels on today’s profligate scale.

Clive Cookson is science editor of the Financial Times