Meloni focuses on the 'clean' energy of nuclear fusion:what does it mean

According to Giorgia Meloni we must aim for the use of clean nuclear energy, that deriving from nuclear fusion:it is inexhaustible and would bring "a better future".But what stage is the research at?

ROME – 'Clean' nuclear energy, deriving from nuclear fusion, as a source to be exploited for the future, above all because it is unlimited:It was Giorgia Meloni who spoke about it this morning on the occasion of the 'Science at the center of the State' event promoted by the Italian Scientists Association (Isa). Clean energy, therefore, the one that forms naturally on the sun and stars.And what artificially it can be produced through nuclear fusion, an operation that has nothing to do with nuclear power plants and bombs and that so far it has only been tested in the laboratory.This is a line of study on which research still has much to discover - and which still requires a long time before it can be produced and used on a large scale - but which according to Prime Minister Meloni will certainly be the future.Meanwhile, here's what Meloni said:“A great perspective, a great vision, a great dream come from possibility of producing clean and unlimited energy from nuclear fusion in the not so distant future.Italy is the homeland of Enrico Fermi, in this regard it is second to none thanks to its know-how, research and development activity, our production system:we can continue to grow, a give the world new discoveries and a better future and different."

FISSION AND FUSION

If it is true that the words are similar, nuclear fusion is very different from fission, which is instead the one that powers existing nuclear power plants.But let's go in order.Nuclear fission is what we know, what exists and powers nuclear power plants and atomic devices.The one from fusion is essentially the energy that powers the stars, the basis of life and the very existence of the universe.The first has not made great progress since its discovery and very soon had extensive industrial applications for energy production, the second has so far only had applications in prototype plants or of laboratory.

WHAT HAPPENS DURING NUCLEAR FISION

The fission reaction was obtained for the first time in the laboratory by Enrico Fermi and collaborators in 1934, recognized and studied experimentally by Otto Hahn and Fritz Strassmann in 1938, interpreted the following year by Otto Robert Frisch and Lisa Meitner (to whom we owe the term) and subsequently studied theoretically by Niels Bohr and collaborators.

In nuclear fission a nucleus with a high atomic number, hit by a neutron, or even by charged particles (protons, deuterons, a particles and others), absorbs them and simultaneously breaks into two fragments each with an atomic number of the order of half the size than that of the original nucleus, plus a certain number of free neutrons.It is a highly exoenergetic reaction – a lot of energy is released – and, also producing secondary neutrons, in appropriate conditions it can self-maintain itself with a chain process.About 1/3 of the energy produced in most nuclear power plants comes from Plutonium which is created in their core as a by-product of Uranium-238.In nuclear power plants, the heat developed by fission reactions allows water to be heated until it produces steam.As in fossil fuel (coal or natural gas) thermoelectric power plants, the energy released in the form of heat is transformed first into mechanical energy and subsequently into electrical energy:the steam produced drives a turbine which, in turn, sets in motion an alternator.

HOW MANY NUCLEAR PLANTS ARE THERE IN THE WORLD

There are approximately 440 plants in operation, led by the United States where 92 are active, followed by France with 56 and China with 55, but it is the country where over 20 power plants are under construction.Nuclear energy, with approximately 413 GigaWatts of operational capacity in 32 countries, provides approximately 10% of global electricity generation while avoiding 1.5 gigatons of global emissions into the atmosphere and 180 billion cubic meters of global gas demand per year. The problem with nuclear power is the very high costs, sometimes unaffordable, and the safety associated with production.All this also involves very long times:the Finnish Olkiluoto 3 (OL3) reactor, one of the last to be built in Europe, began regular production only more than 18 years after construction began.

NUCLEAR FUSION IN THE STARS

Nuclear fusion occurs spontaneously in the Sun and other stars, where the very high internal temperature favors the fusion reaction of hydrogen nuclei (proton-proton reaction).From fusion comes the energy that reaches the Earth in the form of heat, electromagnetic radiation and particles.In fusion, two nuclei of light elements, such as deuterium and tritium, at high temperatures and pressures, fuse to form nuclei of heavier elements such as helium with the emission of large quantities of energy. The energy and heavy elements that we find in the Universe and also on our Planet are therefore formed in stellar furnaces.Nuclei can fuse only at very short distances and the speed at which they collide must be very high.Their kinetic energy – and therefore the temperature – must be very high.

HOW NUCLEAR FUSION WORKS IN THE LABORATORY

To obtain fusion reactions in the laboratory it is necessary to bring a mixture of deuterium and tritium to very high temperatures (100 million degrees) for sufficiently long times.Because of this the challenge of fusion is above all the containment of this plasma at very high temperatures, which we try to obtain with powerful magnetic fields and absolutely special materials.To achieve the fusion reaction, the hydrogen plasma must be confined in a limited space:in the sun this occurs due to the enormous gravitational forces at play.To obtain controlled fusion in the laboratory, with a positive energy balance, it is necessary to heat a deuterium-tritium plasma to much higher temperatures (100 million degrees), keeping it confined in a limited space for a sufficient time for the energy released by fusion reactions can compensate for both the losses and the energy used to produce it. Fusion does not produce waste but as we understand it is very difficult to make it usable on an industrial scale, which will only happen in decades, 50 to 70 years.

THE FIRST FUSION REACTOR IS COMING, THE ROLE OF ITALY

The European Roadmap towards fusion electricity envisages the realization of the first reactor to feed electricity into the grid.The Joint European Torus (JET), the world's largest nuclear fusion experiment, achieved a new record of energy produced during the last and final experimental campaign, demonstrating the ability to reliably generate fusion energy.The main European laboratories coordinated by EUROfusion contributed to the success of the experiments. Italy is a partner with ENEA, the National Research Council, the RFX Consortium and some universities.In the USA, last year the National Ignition Facility in Livermore, California, demonstrated with 192 lasers that it can repeatedly achieve reactions that produce more energy than they consume.The result is a milestone on the long road to clean energy production and virtually inexhaustible.

THE (SLOW) PROGRESS OF NUCLEAR FISSION

For nuclear fission, however, we speak of fourth generation, which however only exists on the planners' paper.The most recent reactors are III generation or III generation plus, essentially the same technology as the 1960s but with redundant and multiplied safety systems. The problem is always the waste for which a definitive geological arrangement has not yet been identified – there is not a single definitive geological deposit in the world – nor an industrial recovery method.Currently the waste is stored in ultra-resistant containers - casks - and stored in active power plants.They are also under study newly developed fission reactors, safer and with less waste production.The projects are different, some even quite promising, but they are still in the laboratories and their industrial scalability is still far away.There is also a lot of talk about Small modular nuclear reactors which are nothing more than small nuclear fission reactors, like those that power ships or submarines.