A gigantic puzzle officially began on Tuesday July 28 in the south of France, with the launch of the assembly of the Iter project reactor in Saint-Paul-lez-Durance (Bouches-du-Rhône). This international program aims to control the production of energy from the fusion of hydrogen, as in the heart of the sun.
[ARCHIVE] Article published on December 31, 2019
This is perhaps where the future of the world is at stake, in the center of Cadarache in Saint-Paul-lez-Durance, about forty kilometers north-east of Aix-en-Provence, at the confluence of the Verdon and the Durance. Giant cranes and huge concrete installations have replaced the pines on this vast plateau where 3,000 people of some thirty different nationalities work every day to carry out what is arguably one of the most important scientific programs ever launched, supposed to end in a quarter of a century.
“Iterville” is a sort of international enclave between the Lubéron and the Alpilles, which covers 200 hectares, the same area as the Principality of Monaco. Here is built the first thermonuclear fusion experimental reactor in the world, Iter, the English acronym for “International Thermonuclear Experimental Reactor”, but also the translation of the word “path” in Latin.
Ten times the temperature of the sun
“A human dream to recreate on earth the limitless energy of the stars from a single water molecule”, enthuses Bernard Bigot, the director general of the project and former boss of the Atomic Energy Commission (CEA), in charge since 2015.
Unlike nuclear reactors where energy is obtained by breaking the nuclei of uranium atoms, Iter’s operation is based on the fusion of hydrogen nuclei, brought to very high temperature. The heat released produces steam, which is converted into electricity by turbines and alternators.
“Our challenge is both size and watchmaker precision. It is necessary to reach 150 million degrees, ten times the temperature of the sun in a box thirty meters high and in diameter with an adjustment of the installations to the nearest half a millimeter ”, explains Bernard Bigot. This huge cauldron is called a “tokamak”, Russian acronym for “toroidal chamber with magnetic coils”, a process developed by Soviet physicists, including Andrei Sakharov. Inside will be installed a kind of air chamber with a double wall of stainless steel in which the plasma will circulate, this fourth state of matter obtained when electrons detach from their nuclei.
An extraordinary site
The civil works of the tokamak were completed on November 8, 2019. “It is one of the most complex projects that we have had to build”, says Jérôme Stubler, president of Vinci Construction. In total, 105,000 m3 concrete and 20,000 tonnes of steel were needed for this 120-meter-wide and 73-meter-high building. “It is large enough to accommodate the Arc de Triomphe”, notes Fabrice Lemaire, who led the work, launched in 2010.
On this pharaonic site, Vinci’s engineers had to develop very specific concretes intended to shield the radiation generated by the fusion reaction. The building rests on 493 columns surmounted by anti-seismic pads. It must be able to support a load of 23,000 tons, or 3.5 times that of the Eiffel Tower. We had to put 750 kg of scrap per m3 concrete in some places, almost ten times more than in a conventional structure. “We are using reinforcement densities rarely reached in structures of this magnitude and without digital 3D design tools, everything would have been much more complicated”, adds Jérôme Stubler. This project was completed on time and within the budget of 700 million euros initially planned.
A scientific bet
But Iter’s adventure is still very long. The next big step is planned for 2025 with the injection of hydrogen and the production of the first plasma. It will take at least ten more years to complete the final adjustments. “Around 2040, we should be able to tell electricians that it is working, and the first reactors could come into service around 2060”, Bernard Bigot forecast. “It may sound like a long time, but we cannot shorten the time. “
Today, in fact, scientists have already succeeded in carrying out nuclear fusion, but only on a very small scale and above all by consuming ten times more energy than was produced. Iter’s objective is the opposite: to obtain 500 megawatts (MW) of fusion power, by injecting only 50 MW. By comparing, “A thermal power station consumes 8 to 10 million fossil fuels per year, against 350 kg of hydrogen with Iter, for the same energy power and without polluting emissions”, assures the former boss of the CEA.
According to him, the process will generate little radioactive waste and only short-lived, of the order of a few decades. “All countries know that our current model of energy production is not sustainable for a planet of 8 billion inhabitants. This explains the success of this international cooperation around the project, the dimension of which is as much scientific as geopolitical ”, says Bernard Bigot.
A project born during the cold war era
Its genesis dates back to 1985 in Geneva, during a summit between the United States and the USSR, in the midst of the Cold War. It was the first meeting between US President Ronald Reagan and his Soviet counterpart Mikhail Gorbachev. They decided to launch a common thermo-nuclear fusion program. The European Union and Japan joined the project in 1987, followed in 2003 by China and South Korea, then India. In 2005, the choice of the site, in Cadarache (Bouches-du-Rhône), which since 1959 has housed a research center of the Atomic Energy Commission (CEA), was made, under pressure from Jacques Chirac, the then President of the Republic.
“Iter’s operation is complex, but I have never seen any dissension between the seven partners who each bring their skills”, says Bernard Bigot. The electrical conversion plant comes from the United States, the superconducting coils are made in Japan, and the cryostat, the largest steel vacuum vessel ever built, arrives from India. The parts are unloaded at the port of Fos-sur-Mer and transit by exceptional convoy to Cadarache on a specially developed road of around one hundred kilometers. “In contempt of the environment”, denounce the opponents.
A budget multiplied by four
Because despite the optimism displayed by the Iter teams, headquartered in Barcelona, critics continue to rain on this project, far from unanimous in the scientific community. Like the Flamanville EPR, this project which promises a “Other nuclear” has also slipped. From five billion euros originally planned, the bill has already reached twenty billion euros, and the schedule has been revised by at least five years.
Within the European Union, which provides 45% of funding, the subject has become very sensitive at a time when renewable energies are on the rise, such as solar, whose costs are constantly falling. Environmentalists are still standing against Iter. “A financial abyss and a scientific chimera”, assures MEP Michèle Rivasi, who calls on the EU to exit “Of this Promethean dream”. In any case, reconstructing the interior of a small sun on earth is not for now.
Fusion, instructions for use
At equal mass, the fusion of light atoms is believed to release four million times more energy than burning oil and four times more than current nuclear fission reactors.
The fuels used are two isotopes natural hydrogen. There is deuterium, easily extracted from water in lakes and oceans, and tritium, which is much rarer on earth. Iter’s engineers plan to produce it on site by irradiating lithium, which would be in sufficient quantity in the earth’s crust.
The fusion does not release into the atmosphere than helium, a chemically inert gas. The radioactive waste produced would be “short lived”.
The fusion reaction is “Inherently safe”, say the promoters of the project. According to them, the major risk is that of a fire.