The ITER program should make it possible to carry out notable advances in nuclear merger for a industrial exploitationas well as other areas of physics such as the study of thermonuclear plasmas.
If the discoveries of the ITER program validated energy production technologies by nuclear fusion, this would open the wayabundant energy, potentially inexhaustible and clean From the end of the century.
How nuclear fusion can produce heat and electricity
The “nuclear fusion” also called “thermonuclear fusion” is the meeting of two light atomic nuclei to form a more heavy nucleus. It is a question of reproducing on earth thermonuclear reactions comparable to those taking place in the heart of the stars. Very large amounts of energy are released by nuclear fusion, as evidenced by the power of modern thermonuclear weapons, the “fusion” bombs. Being able to reproduce this phenomenon by controlling it within a reactor would, in theory, satisfy a large part of the energy needs of humanity.
During the fusion reaction, the mass of the nucleus produced is less than the sum of the masses of the light nuclei of origin. However, under the relationship established by Albert Einstein “E = MC2 », The difference in mass is converted into energy. This energy clearance manifests itself, among other things, in the form of isolated neutrons loaded with energy.
The phenomenon of nuclear fusion therefore differs from that of nuclear fission. In the latter, a heavy atom split into two lighter and more stable atoms with a clearly lower energy clearance.
The ITER reactor’s plans use a magnetic confinement room concept invented in the 1950s called “Tokamak”. This room has two main roles:
- Get and contain fusion reactions within a magnetic shield. Since it is intangible, this shield can withstand the necessary temperatures (150 million degrees Celsius) at the start of the fusion process;
- Collect the energy transmitted by neutrons with the internal walls of Tokamak, to transform it into heat. In the ITER installation, this heat is evacuated using cooling towers. In the Demo fusion reactor prototype, already envisaged to succeed it, the heat will be used to produce steam and, by means of turbines and alternators, electricity.
The amount of energy produced by the fusion reaction is approximately 4 million times greater than that generated by chemical reactions such as the combustion of coal, oil or natural gas. A coal -fired power plant of 1,000 MW burns 2.7 million tonnes of coal per year. An equivalent capacity merger power plant would only consume 250 kilos of fuel each year, according to project leaders.
The two main scientific objectives of ITER
Power
Generate a power of 500 megawatts by being powered by a power of 50 megawatts, for a time of the order of 6 min.
The ratio Q ≥ 10 Symbolizes this first scientific objective: to produce ten times more energy than the machine will have received. Designed to produce 500 MW of fusion energy from an external contribution of 50 MW, ITER could be the first controlled merger device capable of generating energy effectively(1).
- Amplification factor (q) : report of the energy released on injected energy.
- Breakeven : English term corresponding to the moment from which plasma produces as much energy as it consumes for its heating (Q = 1).
- Ignition : Plasma heating is fully ensured by the supply of heat from helium nuclei created during fusion reactions. Additional heating modes can be cut (Q = infinite).
By way of comparison, the world record established by the European reactor “Jet” (Joint European Torus) in England in 1997 was only 16 megawatts for a second, for an injected power of 25 megawatts (Q = 0.67).
Temps
Maintain the merger reactions in the plasma for at least a quarter of an hour(2). For comparison, Tore Supra (Tokamak of Cadarache Research) has held the world record for a fully controlled plasma, for 6 minutes 30 million at a temperature of 40 million degrees since December 4, 2003.
Discoveries on the merger process must be both qualitative and quantitative. Scientists seek to increase the temperature and duration of a plasma a little more, up to the combustion threshold and the self-entrepreneurized fusion (“ignition”).
Industrialisation
ITER is a step towards a pre -industrial installation which will have to demonstrate the feasibility of electricity production. The next step, with the Demo demonstration reactor, should demonstrate continuous energy production, which supposes, in particular, the regeneration of tritium from lithium (for ITER, tritium will be supplied externally from Canadian heavy water reactors) and the use of new materials capable of resisting important flows of energy neutrons. If everything goes as planned, Demo will inaugurate the era of the industrial nuclear merger.
« At the end of 2035 we will start to make real fusion energy production, and the reactor will operate at full power, at 500MW, at the end of 2036 ”and not in 2025-2027 as previously envisaged, said Mr. Bigot, former boss of the French atomic energy police station (CEA) and director general of the 2015 ITER program for his death in 2022. While the viability of the program of experimental nuclear fusion reactor was questioned, some of the countries then considering questioning their participation, Bernard Bigot had put him back on the rails.
The deadline announced for a large -scale deployment is at The second part of the 21st century.
