Understanding nuclear fusion, stellar energy, in 7 questions

An old sea serpent of energy policies, nuclear fusion is coming back to the fore, thanks to the return of favor to the nuclear industry. Thus, the recent bill aimed at reducing inflation and mitigating climate change passed in the United States (“Inflation Reduction Act”) allocates $280 million to the National Nuclear Fusion Development Program. The bottom line in seven questions about this technology that has fueled the hopes and imaginations of scientists for nearly a century.

1. What is nuclear fusion?

Nuclear fusion is a nuclear reaction in which two atomic nuclei fuse together to create a new, heavier nucleus. This reaction is at work in the Sun and in almost all the stars in our universe, leading many observers to refer to nuclear fusion as “stellar energy”.

During this operation, a very large amount of energy is created, which theoretically could be used to produce electricity in new generations of nuclear power plants.

2. What is the difference with nuclear fission?

While nuclear fusion consists of the fusion of two light atoms – such as hydrogen for example -, nuclear fission is the opposite reaction: a heavy nucleus is split in two under the influence of a neutron, a small particle present in the nuclei of all atoms. In current nuclear power plants, uranium is the element that consists of heavy nuclei that will be split under the impulse of a neutron.

Fission is also accompanied by a large release of energy and at the same time the release of other neutrons, which in turn will break other nuclei, releasing energy and releasing other neutrons, and so on. This is called a chain reaction.

3. What are the advantages of nuclear fusion?

The main advantage of nuclear fusion is that it releases a much greater amount of energy than fission, while producing no radioactive waste for thousands of years. Additionally, relying on hydrogen nuclei – deuterium and tritium – the process would provide clean and virtually inexhaustible energy. Deuterium is found in water, and tritium is easily produced from lithium, a metal abundant in the earth’s and ocean’s crust.

Proponents of nuclear fusion also promote another benefit of a safety nature, namely the absence of the possibility of a nuclear accident. In the event of a problem, the plasma in a nuclear fusion reactor cools down in seconds and the reactions are stopped. There would therefore be no risk of runaways that would endanger the nuclear power plant.

4. Which countries are active in the area?

The first research into nuclear fusion began in the 1920s in England. This fever will gradually win many developed countries after World War II, including the USA, USSR, England, France, Germany and Japan.

But it was not until the 1980s that the outlines of an international collaboration were drawn. At the 1985 Geneva summit, the two superpowers, the US and the Soviet Union, agreed to work hand in hand to develop nuclear fusion.

This approximation finds a concrete application in the Iter project. Located in Saint-Paul-Lez-Durance, in the Bouches-du-Rhône, this international initiative, costing 20 billion euros, brings together 35 countries, including the countries of the European Union, Russia, the United States and China.

Tokamak at the heart of the Iter nuclear power plant in Caradache (Bouches-du-Rhône).Daniel Cole/AP/SIPA

Its goal is to reach an industrial application of this technology with the construction of a civilian nuclear reactor with nuclear fusion. Currently in the assembly phase, the reactor is due to perform its first test in 2025.

5. Is nuclear fusion really clean energy?

In theory, nuclear fusion should be used to produce clean energy and four times more consistently than the energy from nuclear fission using the same fuel. The process also releases no CO2 and generates only helium, a non-toxic gas that is not part of the greenhouse gas family.

However, if nuclear fusion power plants do not produce any long-lived high-level radioactive waste, they still generate radioactive waste.

Jérôme Bucalossi, director of the Institute for Research on Fusion by Magnetic Confinement (IRFM) at the Atomic Energy Commission (CEA), nevertheless explained to “Echos” that the radioactivity of this waste “could be deactivated in about ten years, a century maximum’, against thousands of years for the most radioactive in the case of a nuclear fission reaction.

But there remains the difficult question of the materials of the plant’s origin – such as beryllium – whose extraction would be polluting.

6. When will nuclear fusion be used concretely?

This is the question that plagues all observers of the sector. For decades, nuclear fusion progress was limited to isolated experiments that set new records for plasma temperatures or sustain times.

In recent years, many projects have been initiated with the aim of having an operational nuclear fusion reactor around 2030. This is the case with the Iter project, which expects trials to begin in 2025. However, many experts agree that industrial use of this the technology is unlikely to emerge before the middle of the century.

Enough to prompt Greenpeace to say that “nuclear fusion remains a mirage on glossy paper” costing “billions of euros of public money with no guarantee of results”.

7. Is the private sector investing in this technology?

Nuclear fusion has long been reserved for states, and nuclear fusion is gaining ground with private companies, including Marvel Fusion. The Bavarian start-up – which has raised almost 65 million euros since its creation – plans to launch a prototype power plant in 2027 before bringing its solution to market in the 2030s.

However, it is in the United States that the frenzy is most intense. Several investors are interested in nuclear fusion, and not least: Jeff Bezos, Bill Gates or even George Soros have all invested in young shoots in the sector.

The Amazon boss is backing Canadian start-up General Fusion – which has also benefited from government investment – ​​in its $400 million nuclear power plant project in Culham, England. Bill Gates and George Soros, for their part, participated in the fundraising of Commonwealth Fusion Systems, which enabled the American company to raise 1.8 billion dollars.

A total of 25 private companies entered the merger business in 2021. Almost $3.5 billion was raised in the markets, according to data from the PitchBook agency.

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