A few days ago the international forum “World Atomic Week” was held in Moscow. The event, organized by Rosatom (Russian national nuclear energy corporation), commemorated 80 years of the industry and intended to serve as a showcase for technological advances and the future of this energy. In this context, the president of Russia, Vladimir Putin, announced that he hopes to put into operation the first closed cycle plant in 2030, a plant capable of reusing 95% of spent fuel. The plant will be in Siberia and would be a milestone for its ability to reduce the volume of atomic waste and the need for mining extraction while extracting more energy for longer.
The key is in the term “closed loop.” Current plants, the vast majority of those in the world including the Spanish ones, use the fuel for 3-4 years and once spent it irremediably transforms into waste. The idea of closed cycle plants is to reprocess spent fuel and return it to the reactor to extract new energy. «The uranium extracted from the mine has 0.7% uranium 235. Before reaching the reactor it undergoes an enrichment process (a maximum of 5% for safety reasons) in which we generate a large amount of uranium 238, which is almost not used. That means that we have kilos and tons of uranium 238, which we are not using but which are there and which They would serve to provide energy for a thousand years. Just think that the oil we have is only 100 years old and commercial nuclear power is 40 years old,” says Óscar Cabellos, professor in the Department of Nuclear Engineering at the Polytechnic University of Madrid. Almost all the plants in operation right now worldwide are light water, that is, they use water for cooling and “in this type of reactor, the fuel is used for 3 or 4 years, until reaching what we call a burn-up, or an energy extraction that corresponds to the order of about 50,000 MW per day for each ton of uranium that is introduced. This “waste” still has an energy potential of up to one million MW,” comments the researcher.
Countries like France, India or China today have reactors and reprocessing plants in which that spent fuel is recycled. They manufacture what is called mixed uranium and plutonium oxides, MOX for short, a mix of depleted uranium and plutonium. «If you analyze the fuel after passing through the reactor, of the uranium 235 that you initially put in there is logically very little left, but a lot of uranium 238 remains. In a plant you can chemically separate isotopes, for example from plutonium that you will use to make a new fuel by mixing it with uranium oxides. This mixture is what we call MOX and it is what is burned again in the plant with certain limits (just as uranium 235 has an enrichment limit) and is operated in the same way. It is said that France’s is a partially closed cycle, because it reuses once that plutonium that has left it as waste. The irradiated MOX is not reprocessed successively,” comments Francisco Álvarez Velarde, researcher at the Center for Energy, Environmental and Technological Research (Ciemat). In fact, conventional light water reactors can only support a single recycling of plutonium and two or three of uranium, according to Russian media.
However, the new BRiEST-OD-300 reactor project, that Russia is building goes one step further. Not only do they have a reprocessing plant, but they The reactor is fast type, that is, it uses lead as a refrigerant instead of light water, which allows the temperature of the reactors to be increased and more fuel to be burned without losing the coolant since the water is transformed into steam above 375 degrees. “It is what you need to have a totally closed cycle in which you can burn MOX and reprocess and burn the same fuel again and again and again,” Álvarez clarifies. These reactors use fuel more efficiently. «Instead of burning up to 50,000 megawatts per day, you can burn much more. Various designs are being worked on; There are fast sodium reactors, lead reactors… facilities that are being built to verify that the technology works, even though they are not yet producing electricity. There are still things to solve, such as the problem of materials because they get damaged, or balancing the economic part,” Cabellos clarifies.
Demand on the rise
It is undeniable that nuclear has returned to public debate reinvigorated, if you can say so, following the IPCC report and COP 28 that recommend triple the number of reactors in the world to produce energy. «We are talking about building 800 reactors in 25 years. An outrage. There is probably no uranium in nature to deal with that much at a reasonable cost. We are talking about that in 20 years we have to do double what we have done in 40,” says Álvarez del Ciemat. On the other hand, there are OECD estimates that uranium resources could be exhausted by 2090. All of this increases interest in developing reprocessing plants and fast reactors, “About 100 tons of plutonium are produced around the world in irradiated fuel each year. A simple recycling increases the energy derived from the original uranium by approximately 12% and if the uranium is recycled it will reach 20%,” explains the Spanish Nuclear Industry Forum.
The countries of the global South and East currently dominate the commitment to the construction of new reactors. «China is building one reactor of each type to decide which technology it will implement on a massive scale. Today it has 57 reactors and is building another 29. For decades, France has wanted to secure its supply and that is why it wants to be knowledgeable about reprocessing when the time comes to replace its entire fleet of reactors with fast models,” comments Francisco Álvarez, from Ciemat. Russia has its own developments as we are seeing and India “is also developing this type of technology because they have a lot of Thorium 232, which they can transform into uranium 233 in this type of reactors in a simple way,” explains the UPM researcher, Óscar Cabellos.
On the other hand, there are the calls SMR or modular nuclear power plants in which Russia or India are very committed. «It is very attractive, for example, for remote areas or countries that have an electrical network that is not capable of absorbing 1,000 MW of electricity, but 100 or 300 and then if you need to expand you add modules. They are promising but of course, we have to start building them. That means it will be expensive. On the other hand, there are the so-called fourth generation reactors that seek greater security with passive systems, that is, they do not need a technician to press a button if something happens, but rather they use physics to provide automatic solutions to problems. In addition, they take sustainability parameters into account and, for example, allow the cycle to be completely closed and waste minimized (the amount of remainder that would later need deep geological storage is divided by 100),” says Cabellos.
From projectiles to the reactor
While fusion arrives, the path of nuclear fission can be widened thanks to new fuels that become fissile. «Uranium 238 is much more abundant and until now it has been considered waste and has only been used in some cases, such as, for example, to make cannon projectiles, because it is a very heavy material. That is, it is not radioactive or has very little radioactivity, but it can be transformed into plutonium 239 and new nuclear fuel. Then there is another fissile isotope, uranium 233. And that uranium 233 is created from thorium 232, another enormously abundant radioactive material that is not used right now. We have it almost in any granite mountain. If we convert uranium 238 into plutonium 239 and thorium 232 into uranium 233, we are generating fuel from isotopes that are currently useless. The availability of nuclear fuel would increase enormously if this were the case, mining would decrease and the plants would in principle be much more profitable. And that would manifest itself in that instead of charging like now every two years, the fuel would be changed every 15. That’s what they say, because since we don’t have any still working, we don’t know,” says José Díaz Medina, from the Institute of Corpuscular Physics at the University of Valencia.
More than 60 plants under construction
►China, Japan and the United States currently lead the construction of nuclear reactors. It is estimated that there are more than 60 under construction right now. In Europe it has also been included in the green taxonomy as a source of energy in which to invest to achieve decarbonization and, although in the old continent there is a lot of social protest, steps are being taken towards nuclear relaunch. Germany, which decided to turn off its reactors after the Fukushima accident, and did so absolutely in 2023, has brought closer positions with France, the absolute nuclear leader in Europe. His government now assures that it will not hinder any initiative to support nuclear energy.