2024-02-20 07:30:05
The world’s largest experimental nuclear fusion reactor was inaugurated on December 1, 2023 in Japan. If it keeps its promises, this potentially infinite source of energy could become a key component of the future energy mix.
The « tokamak[1] », JT-60SA[2]15.5 meters high, was presented last December on the QST website[3] in Naka, about a hundred kilometers northeast of Tokyo. Resulting from the Japanese-European experimental nuclear fusion project called “star energy”, it is complementary to the ITER program.[4] under construction in Cadarache, France.
Despite the delay accumulated on the project[5]this inauguration marks the successful collaboration of more than 500 scientists and engineers and 70 companies in Europe and Japan.
The physical reaction that makes the stars shine
Nuclear fusion generates light and heat through to the gigantic energy released at the heart of the sun when light nuclei (hydrogen) collide at very high speed in the plasma[6] and at very high temperatures (15 million degrees Celsius) to fuse into a heavy helium core. It differs from nuclear fission, currently used in nuclear power plants, consisting of breaking a uranium nucleus to release energy. Fusion does not have the disadvantages of fission reactors sinceit releases little radioactive waste, which also has a short lifespan.
Nuclear fusion with megamagnets
In order to artificially recreate in the tokamak the physical reaction taking place at the center of the sun and cause the fusion of hydrogen and deuterium (a stable isotope of hydrogen), it is necessary to heat and maintain plasma at extremely high temperatures ( more than a hundred million degrees Celsius). To prevent this material from cooling, an extremely powerful magnetic field must be produced by confining plasma using superconducting megamagnets half of which was produced in Belfort by GE Power. On October 23, this tokamak succeeded to create plasma for the first time for several seconds with a record volume of 160 cubic meters. This technology is only advantageous if the reaction produces more energy than it consumes.
JT-60SA, little brother of ITER
The JT-60SA tokamak is a sort of laboratory used to refine the fusion device before the completion of ITER, which is part of an international cooperation program bringing together thirty-five countries. This will be approximately twice as large and will have nearly five times the plasma volume capacity to the JT-60SA tokamak. Originally planned for 2025, ITER’s first plasma production is constantly delayed due to delivery problems or insufficient quality of essential parts. According to Pietro Barabaschi, general director of the project, the gigantic ITER construction site « finds himself in a very difficult situation ». These complications generate additional costs since the construction budget initially estimated at 5 billion euros will ultimately exceed 20 billion euros.
[1] Russian acronym for experimental reactors dedicated to nuclear fusion
[2] SA for Super Advanced
[3] National Institutes for Quantum Science and Technology
[4] International Thermonuclear Experimental Reactor
[5] Particularly because of its proximity to the great earthquake of 2011 on the northeast coast of Japan
[6] State of matter consisting of charged particles (ions) obtained at very high temperature.
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