Thermonuclear Breakthrough: Are Fusion Power Plants the Future?
The JET reactor obtained a whopping 69 megajoules from just 0.2 milligrams of fuel. Scientists claim that if everything goes according to plan, in the future, thermonuclear reactors will provide us with cheap and safe energy.
The record was set during experiments at JET (Joint European Torus). This reactor is located near Oxford in the United Kingdom. It is also one of the largest and most powerful thermonuclear installations in the world.
What is thermonuclear fusion?
Thermonuclear energy is produced as a result of fusion — the merging of nuclei of light atomic elements. This process occurs naturally inside stars, where atoms are compressed by tremendous pressure. On Earth, isotopes, heavier variants of hydrogen, can be used for this purpose: deuterium and tritium. The former has a proton and a neutron in its nucleus and is quite common in water.
The latter, however, is composed of a proton and two neutrons. It does not occur naturally, but it can be easily obtained from lithium. Using tritium as fuel along with deuterium yields more energy while also increasing the level of radiation in the reactor.
JET is a tokamak-type reactor — a chamber shaped like a torus (or a donut with a hole). Inside it, a magnetic field confines the heated gas, or plasma. It must reach enormous temperatures, around 100 million degrees Celsius, for thermonuclear reactions to occur. In 2021, the JET reactor achieved thermonuclear energy from tritium atoms for the first time. This was a dress rehearsal before the operation of a large installation called ITER.
JET has served scientists for 40 years. It was finally decommissioned in the autumn of 2023. However, it managed to break the record before that.
Tokamak fusion record
In the final experiments conducted at JET, deuterium and tritium were used. The thermonuclear reaction was sustained for 5 seconds. During this time, a record power output was achieved. 69 megajoules of energy were produced using only 0.2 milligrams of fuel.
– During these studies, we demonstrated, among other things, how to bring plasma to a stable state, preventing damage to the reactor wall. For the first time in history, we managed to test this during the fusion of deuterium and tritium — emphasizes Dr. Emmanuel Joffrin, one of the scientists involved in the research.
More than 300 scientists and engineers from EUROfusion — a consortium of researchers from across Europe — participated in the research. JET will be dismantled and disposed of over the next 15 years. Some of its components will be used in other devices.
How efficient is thermonuclear fusion?
One gram of hydrogen “burned” in a thermonuclear reactor can produce as much energy as 8 tons of crude oil or 11 tons of coal. To meet the world’s energy demand, only a few hundred kilograms of hydrogen isotopes (deuterium and tritium), which can be obtained from seawater, would be sufficient annually.
Thermonuclear power plants will be safer than nuclear ones. They are also expected to produce significantly less radioactive waste. However, before this happens, scientists need to refine the technology. This includes ensuring that the thermonuclear reaction produces more energy than is required to initiate it. In the case of JET, three times more energy was consumed than was obtained, so there was no surplus.
The results of the experiments at JET will be used in the construction of ITER. This is a huge reactor being built in France, financed by the European Union, China, India, Japan, Korea, Russia, and the USA at a cost of 22 billion dollars. The first operation of ITER is planned after 2025. After 2035, the reactor is expected to operate on a mixture of deuterium and tritium. If everything goes according to plan, it will be the first installation to generate surplus energy from thermonuclear fusion.
Other such installations include the British prototype power plant STEP and the European demonstrational power plant DEMO. They too will benefit from the research conducted at JET. These reactors will start operating after 2040. This means that until then, the energy transition must rely on renewable energy sources and nuclear power plants.
Other thermonuclear fusion research
Tokamaks are not the only way to achieve thermonuclear fusion. Scientists are also working on alternative methods.
- A type of thermonuclear reactor different from the tokamak is the so-called stellarator. Its chamber has a complex, twisted shape that facilitates plasma control using a magnetic field. In Germany, the Wendelstein 7-X stellarator is operational. It cost significantly less than ITER, only 2 billion euros.
- A different approach to fusion is being tested at the American National Ignition Facility (NIF), part of the Lawrence Livermore National Laboratory. Scientists compress and heat hydrogen isotopes there using lasers. In 2022, for the first time, the NIF thermonuclear reactor produced surplus energy. Subsequent tests confirmed this achievement.
Scientists involved in the JET project emphasize that these studies complement each other. — Thanks to them, our knowledge of plasma and thermonuclear reactions is expanding — said Dr. Athina Kappatou from the Max Planck Institute for Plasma Physics at a press conference.
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