Having a star at hand is the dream of every nuclear physique. An impossible mission that researchers from all over the world are trying to complete. Because producing energy, just as our sun does, could solve our dependence on fossil fuels and climate change in one go. Reproducing nuclear merger, in smaller stairs, would mean getting more energy than you enter to feed the system: a not zero -sum game. To get to this goal, the road is still long, but a fundamental stop of research passes from Frascati, just under twenty kilometers from the Colosseum. It is the DTT (Divertor Tokamak Test) which will be built in the research center of the National Agency for new technologies, energy and sustainable development (ENEA).
What is nuclear fusion
We start from the bases, from the atoms, some of the smallest structures that make up what we know. The atoms are made up of several positively charged particles (protons) or negatively (electrons) and electrically neutral particles (neutrons). In the last century, scientists discovered how to obtain energy from the fission, that is, the split, of the atom. Thanks to the “bombing” of heavier nuclei, through neutrons, the bonds of sub-atomic particles could be caused and therefore triggering a chain reaction that freed an energy never seen. And that at war could be used to make a bomb, hence the idea for the devices that disintegrated Hiroshima and Nagasaki.
If for the fission we speak of division, in nuclear fusion the atoms come together. And in doing so they also release a large amount of energy. But to achieve this result, atoms must be obliged to get in touch and therefore overcome their electromagnetic repulsion. This is what happens in the sun where, however, in addition to the very high temperatures there are enormous gravitational forces that “crush” atoms. Conditions that are difficult to replicate on earth.
To remedy these obstacles, there are two solutions roughly: the magnetic confinement fusion (exploited by the DTT) and the inertial confinement fusion. Without going too far into technicalities, the first option tries to simulate what happens in the sun. Plasma (a particular state of matter) is overheated at over 100 million degrees and “restricted” in a smaller area thanks to a magnetic field so as not to destroy the reactor. In the inertial confinement fusion, on the other hand, the plasma is heated through laser rays.
From process to demo
Since 1957, with the signature of the Treaty of Rome that has established Euratom, Europe chases the dream of the development of nuclear energy for peaceful use. First with the fission and then with the merger. In 1983, in the United Kingdom, he started operating the jet merger reactor who achieved an important first result. In 1997 he obtained a merger energy profit factor (Q) equal to 0.67. He produced 16.1 MW of energy with 24 MW entered to make the reactor work. In a nutshell, Jet had approached but had not reached, the energy draw (q = 1). In 2023 the disposal of the British reactor began. But the European Union together with China, the United States and other countries has launched the process project with even more ambitious purposes: generating more energy than it is needed to make the reactor operational.
Iter is an intergovernmental organization that aims to develop a reactor capable of obtaining an energy gain (Q) equal to 10. That is to generate 500 MW with 50 MW of power in place. The reactor will be built in Cadarache (near Marseille). The production of merger reactions was postponed to 2039, with a delay of four years compared to the scheduled roadmap. And costs should rise up to $ 25 billion.
At the same time, the European Union in 2014 created the Eurofusion program that supports and finances research activities on the merger on behalf of Euratom (from which he received between 2021 and 2025 549.4 million euros). The program has relaunched a roadmap to develop iter and demo projects. The latter aims to demonstrate – hence the name Demstration Power Plant – the possibility of creating a prototype of fusion nuclear reactor capable of providing electricity, even if not commercially. Demo reactors are the last step before arriving at a hypothetical production of large consumer electricity from merger power plants. The demo project should enter its operational phase around 2050. But to get to the final goal, Italy will also have to do its part. And indeed it will be fundamental.
What is DTT
The Eurofusion program identified 8 missions to be reached to get to the production of commercial electricity. Here the DTT of Frascati comes into play which will have to find a way to make the heat unloading accumulated within the reactor (“Heat-Exaust System-Mission 2”).
But let’s take a few steps back. The Italian project begins to take shape in 2018 when Frascati is selected as a reactor site. In 2019 the DTT Scarl (limited liability consortium company) is formed, which sees a partnership of public and private bodies. The Enea agency holds about 70 percent of the shares, Eni 25% and the remaining 5% are divided by the consortia also made up of many Italian universities including the Polytechnic of Turin and Tor Vergata. The duration of the company is set at 31 December 2050.
The Divertor Tokamak Test is nothing more than an magnetic confinement type of fusion reactor. Tokamak is a particular type of reactor and the term indicates both the donut (Toroidal) shape of the chamber where the merger takes place, and the magnetic field that is generated to confine the plasma. Inside the reactor two isotopes of hydrogen, deuterio and trizio are merged, more than 100 million degrees centigrade. The reaction generates energy: one part is dispersed in the form of neutrons and the other circulates in the room in the form of plasma. The magnetic field must ensure the stability of the ionized gas and prevent it from approaching too much on the walls of the reactor. The structure, in fact, must resist temperatures that would be recorded on the surface of the sun.
For this reason, the diverter’s task, a plate located at the bottom of the reaction chamber, is fundamental. It must bear the very high temperatures and allow the heat unloading. In the near future this heat will allow to produce the steam that will operate turbines which, in turn, will generate electricity. The DTT does not have this task, entrusted to the hypothetical demo reactor, but will have to demonstrate that we are able to build objects capable of resisting thermal stress never seen.
Costs and times
In the last financial statements, at 31 December 2023, the construction costs of the plant amount to 701 million euros, compared to the 500 million estimated in 2015 (in the Project Proposal Report – Blue Book) and 614 million calculated later. To this total, it is underlined, 15 million must be added for the risk of increasing costs due to inflation and an amount of 75 million due to market risks. In addition, the tender for the “supply of 18 containment crates of the bull magnet modules” was awarded by De Pretto Industrie at 29,895,800 euros compared to the 22 million of the basic amount. And the speakers perform a non -second floor function, given that they provide structural support by contrasting the forces generated by the current and the magnetic field powered by the system.
The entire construction budget is ensured by the ENEA company that has obtained the necessary resources from different sources of financing including: the European Fund for Strategic Investments Feis, pillar of the Juncker plan (250 million euros); the EuroFusion European Consortium (about 60 million euros); the Lazio Region (25 million euros in the POR FESR 2014-20 and 34 million euros plus VAT from other regional funds); from the PNRR (55 million euros, DTT-IT project); by the Ministry of University and Research; by the Ministry of the Environment; from own funds.
Also in the financial statements, it is read that the “time schedule provides a further slip of the date of the first plasma”, or the first tests with the ionized gas inside the reactor. No more between the end of 2029 and the first half of 2030, but December 2030 after the completion of the construction works in April of that year. The reasons for this delay are linked to the creation of the Tokamak Hall, the reactor’s assembly room. And precisely on May 15, the tender for the design and construction of this structure and auxiliary buildings was published. In particular, the Tokamak Hall will have a square plant of about 35 meters per side, with an internal height of over 26 meters, and will be built with walls 2.2 meters in reinforced concrete, designed to ensure maximum safety and stability. The total amount of the contract is 76,477,341.87 euros, the deadline for submitting the offers is set on 23 July. The DTT project then goes on and with it the dream of nuclear fusion.
