New materials, technologies and processes to make the use of nuclear fusion possible

Climate change is one of the greatest challenges of our time. And it is not yet clear that we are really in a position to overcome it. There is a broad international consensus on its seriousness; the targets to be met are known and by what dates it will be essential to meet them; many of the solutions to be applied have been identified and important steps forward are being taken in their implementation…, but it is also known that the difficulties in achieving them are many and of extraordinary magnitude.

One of them is how to make the increase in energy consumption compatible with the decarbonization of the economy. Indeed, despite the great advances in energy efficiency that are being made, it seems clear that global energy demand will inevitably be driven significantly in the coming years by economic growth which, especially in the less developed areas of the globe, is necessary to ensure better living conditions for all citizens. In fact, it is currently estimated that global energy consumption will grow by almost 50% between 2018 and 2050, mainly due to strong economic development in some regions and population growth.

Ensuring that this does not jeopardize the unavoidable objective of promoting the decarbonization of the economy – for example, by aiming for a climate-neutral Europe by 2050, as the European Union has done – requires, among other initiatives, a massive deployment of renewable energies.

However, while the progress being made in this area is also very significant, the fact remains that the main renewable sources currently available have a number of intrinsic limitations, such as diffuse nature, intermittency and variability.

For this reason, an energy alternative that has been in the pipeline for many years and whose maturation would facilitate the availability of energy in quantities compatible with the great challenge we face is becoming increasingly relevant. This is fusion energy.

In a very elementary way, nuclear fusion energy can be said to be the “reverse version” of nuclear fission energy. It is a reaction in which the nucleus of a heavy atom splits into two or more nuclei of lighter atoms when a neutron hits the first one, generating large amounts of energy, as happens in nuclear power plants.

A nuclear fusion reaction is a reaction in which two nuclei of light atoms, usually hydrogen and its isotopes (deuterium and tritium), join together to form another heavier nucleus, releasing enormous amounts of energy in the process. Basically, this is the type of reaction that occurs continuously in the sun and stars.

In order to achieve a nuclear fusion reaction, extraordinarily high levels of energy are needed to bring the nuclei of the light elements used in the process close together at very short distances where the force of nuclear attraction exceeds the forces of repulsion.

This requires, among other complex requirements, the use of particle accelerators or heating processes at very high temperatures until a gaseous mass, called a plasma, is achieved, which must have a high density and be confined at these high temperatures for the time necessary for the fusion reaction to take place.

One of the most important breakthroughs on this difficult path was the agreement in 2006 by the European Union, Japan, the United States, South Korea, India, Russia and China to develop an experimental nuclear fusion reactor, called ITER (International Thermonuclear Experimental Reactor), which is still under construction in the south of France.

The next major step in this roadmap is the development of another fusion reactor, in this case a demonstration reactor, to generate electricity. This is the so-called DEMO (DEMOnstration Power Station).

Making the technological leap needed to make DEMO possible requires materials capable of withstanding intense and prolonged neutron irradiation. For this reason, the European Fusion Programme is considering the development of DONES (DEMO-Oriented Neutron Source), a facility capable of producing a high neutron flux that will make it possible to investigate the behaviour of the materials required for the construction of future fusion reactors.