Star power: the Irish role in a French nuclear reactor
Irish scientists on the Iter nuclear fusion project in Provence are helping to build the world’s most complex machine
An aerial shot of the Iter site this year
The world’s most complex machine is being built on a hilltop in the south of France. It aims to recreate the power of stars through nuclear fusion (not fission) and promises boundless energy with no greenhouse gases. Irish scientists and engineers are key players in this ambitious project, helping to develop the reactor in the Provence countryside.
The reactor, dubbed Iter (International Thermonuclear Experimental Reactor), will heat a dense soup of gas particles to 150 million degrees. Hydrogen nuclei will then bang together and fuse, releasing nuclear energy. It poses none of the risks of regular nuclear power, the scientists promise, but critics deride the machine as a colossal waste of money.
We know fusion works because it powers the sun, where hydrogens combine due to gravity and high temperature to produce helium and the energy released we’ve enjoyed this summer. Here on Earth, scientists will hold searing hot plasma in place using giant superconducting magnets, which will keep it away from the walls of its vacuum chamber.
“When you heat gas up sufficiently, it becomes ionised, so you end up with free electrons and positively charged ions,” says Miles Turner, director of the National Centre for Plasma Science and Technology in DCU. “So you get nuclear chemistry rather than your ordinary electron chemistry.”
Releasing the power of an atomic nucleus means more energy. In fact, it will release almost a million times more binding energy than burning coal, which just moves electrons around. Just a single gram of two types of hydrogen nuclei will generate the same energy as 8,000 litres of oil.
‘A soup of particles’
One way the plasma is fizzed up is by sending a beam through the magnetic field.
Irish scientist Deirdre Boilson heads up this effort in Iter. “Plasma is like a big soup of particles. When my beam goes in there it inevitably collides with these other particles and so gives energy to them,” the Castlebar native says. Boilson first got involved in fusion science in DCU, before she moved to sunny Aix-en-Provence to work on the Iter project.
Temperature for a scientist such as Boilson is a measure not of heat but of the average speed of particles. As a room warms, atoms and molecules increase their velocity.
Smashing two types of hydrogen – deuterium and tritium – produces high- energy neutron particles. It is difficult even to test materials’ ability to withstand these particles because they are not present naturally and cannot easily be produced.
Brian Macklin, a graduate of NUI Galway, is responsible for installation of the vacuum vessel, the heart of the reactor. A special route has been developed - with roads upgraded and widened – to allow the colossal parts be convoyed in from a port close to Marseille.
The size and weight of components and the fact that they have to be aligned so precisely poses a major engineering challenge, says Macklin.
“There are 17m-high components weighing, say, 400 tons that require alignment precision of two to three millimetres. Just parking your car to two to three millimetres’ precision would be a challenge for most people,” he says.
The machine comprises about a million parts. These will be made all around the world and shipped to the French site for assembly, which will involve about 4,000 construction workers.