Controlled thermonuclear fusion is a long-awaited goal in the nuclear physics community. Unfortunately, building a reactor where it occurs is thousands of times more complicated than the fission one. We have proof that the first fission reactor, the Chicago Pile-1, was built during the Manhattan project and in just over a decade, on June 27, 1954, the Obninsk Nuclear Plant in the Soviet Union was connected to the electrical grid providing about 5 megawatts of power. The case of fusion is quite the opposite: the first controlled fusion experiment was carried out at the Los Alamos National Laboratory (USA) in 1958 and after more than half a century of research, with hundreds of billions of euros invested , we still do not see the light at the end of the tunnel.
One of the great problems that has not yet been solved is keeping the plasma stable long enough for fusion to occur. In the JET (Joint European Torus), the large magnetic confinement reactor located at the Culham Fusion Energy Center in England, the maximum lifetime they have reached is 30 seconds. In addition, this reactor holds the world record for energy production by nuclear fusion: in 1997 it produced 16 megawatts. Unfortunately generating energy is not enough; what has to happen is that more is produced than is consumed.
Spend less and produce more
This is the other great challenge of nuclear fusion: that the so-called gain factor, Q, which represents the ratio between the energy produced by the reactor and the energy needed to maintain the plasma in a steady state, is at least equal to 1 Or what is the same, that at least we extract from the reactor the amount of energy necessary for it to work; is what is called the break-even . In the case of JET, these 16 MW were obtained at the cost of an energy injection of 24 MW, which means a Q value of 0.7, far removed from Q = 5, which is what is needed for a self-sustaining reaction (since the helium nuclei produced carry away a fifth of the fusion energy) and even further from the Q = 10 required by a commercial fusion plant.
Currently, most physicists working in this billion-dollar field of research think that this will only be achieved with another type of magnetic confinement, called a tokamak: a donut-shaped tube wrapped in superconducting coils that create a powerful magnetic field. magnetic in order to keep the plasma floating inside. Of all the possible designs, the greatest hope is pinned on the tokamak being built in the French town of Cadarache. It is ITER ( International Thermonuclear Experimental Reactor) , a consortium of the six most powerful nations in the world and Europe.
To speak of nuclear fusion is to mention what is possibly the most powerful community of scientists in the world: the figures they handle always have more than 8 zeros. For example, the cost of the US National Ignition Facility (NIF) reached 5.3 billion dollars, the German Wendelstein 7-X reactor 1 billion euros and ITER would not be uncommon if it exceeded 30 billion.
The problem with such pharaonic and multimillion-dollar projects is that any initial estimate of what it will cost the public treasury -because it is the citizenry that puts each euro spent- always falls short. The Wendelstein 7-X was budgeted at 350 million and has cost triple; the ITER project, which in 2006 was projected with a disbursement of 5,000 million euros, 6 years later the extra cost already rose to more than the initial 67%.
An increasingly distant future
The evil that haunts nuclear fusion is the underestimation of costs and the overestimation of deadlines. An obvious example is the monstrous ITER, which has seen nothing but delays. Initial expectations predicted its entry into operation in 2016; now it is speculated with 2027 and it is not even sure of that. In 2010, the ITER consortium announced on its website that in 2040 the first nuclear fusion plant would already be connected to the electricity grid. At present, if you have generated your first plasma by then, it will be a success. All this raises critical voices against this economic black hole of research , which swallows up tens of billions of euros that could very well be devoted to exploring or improving the efficiency of other energy sources, such as renewables, which do we know they work. The uneasiness is evident: at present those responsible for ITER fear that “the project could be seen as a huge failure”.
Suppose that ITER, on an undetermined date, achieves its objective, reaching break-even , its Q = 1. Would we already have the merger in our pocket? Unfortunately, no. Even if it works as it is believed to, energy production will have to wait for the construction and start-up of DEMO, the first experimental nuclear fusion plant, scheduled -that is to say- for 2033. With it, it will seek to demonstrate that fusion it is a profitable business, that is, a Q = 10 is reached.
The problems of commercial nuclear fusion
The problems facing DEMO design are immense and no one knows how to attack them. One of the trickiest is a subject we know virtually nothing about: how to convert the released energy into electricity. The designs – all on paper – involve building a ‘wrapping’ around the reactor core that collects the neutrons that are produced and converts their kinetic energy into heat: it is called “the blanket”. To summarize, this ‘blanket’ must be able to absorb a large amount of heat without overheating, and absorb the neutrons coming from the fusion to use them to convert lithium into tritium, necessary to maintain the reaction, with a perfect efficiency of 100%. . And all of this still needs to be investigated and seen if it is technologically possible. Not surprisingly, Mohamed Abdou, director of the Center for Fusion Science and Technology at the University of California, Los Angeles, believes that “it will take us 30 to 75 years to understand things well enough to start building an operational plant.” . Which brings us directly to the year 2100. But like a good nuclear physicist, he takes his particular leap of faith: “I think it can be done, but it will take a lot of work.”
If there is one thing that cannot be denied to the community of nuclear fusion physicists, it is their unwavering faith that one day soon they will achieve it. In fact, their favorite mantra is something they have been saying since 1980: “in 20 years it will be working”. Unfortunately, in the face of this plasma-proof faith is what history reveals to us: the merger progresses very slowly, and at each step everything that was taken for granted in the previous step has to be changed and retouched.
After six decades we still don’t know if the dream will come true. Can we prevent achieving commercial thermonuclear fusion from ending up in the history books as one of the biggest fiascoes in modern science?
References:
ITER – the way to new energy
