Nuclear: Soon a disruptive technology?
We are very proud to share with you today the last part of a set of 4 documents that present a great overview of the nuclear landscape. Epsiloon, a French magazine that reinvents the scientific press and that is independent, high-standard, committed and sincere. All traits that are also at the core of inTechBrew.
In this series of blogs, originally published (in French) in December 2022, we will go through nuclear’s new golden age, the challenge of long-term maintenance, the SMRs race and finish by presenting you the other potentially game-changing innovations of our nuclear future. Although some examples given in this specific article of our series with Epsiloon refer to the French landscape, the points made can easily apply to the global nuclear landscape.
This last instalment is offering to review today’s new options for nuclear.
Importantly, and before we start, we would like to thanks @Herve Poirier for trusting us with Epsiloon’s work. The set of articles was originally written by @Vincent Nouyrigat, @Pierre-Yves Bocquet, @Xavier Boivinet and @Muriel Valin for the December 2022 issue of Epsiloon.
Originally written in French, the translation and revision for an international audience was completed by @Xavier Poteau for inTechBrew.
Nuclear: Soon a disruptive technology?
Every week gets its lot of tremendous announcements, promising publications, enthusiastic start-ups… “At the moment, there is hyper-communication on nuclear research,” points out Alexis Nuttin, a French nuclear researcher at IN2P3 (the French National institute of nuclear and particle physics). “As soon as a Chinese lab announces results, an American follows suit. Not to mention the dozens of start-ups that are on a war footing to attract funding. »
It must be said that there are big stakes around new technologies likely to replace current reactors. The current global fleet consists of more than 400 fission reactors: the heat produced by broken uranium nuclei is transmitted to water, which turns the turbines. 70% are so-called “pressurized water” reactors (the famous PWRs), the others, boiling water, heavy water, gas, being variants.
Great stuff, but this technology, which is in its third generation, still has to answer challenges of security, reliability, proliferation and depletion of uranium resources… The current technology is also incapable of directly providing heat to some industrial process. An important scenario in the in the context of global warming and unprecedented energy crisis. “Some industries, particularly in the chemical and steel industries, need to operate with water vapour at more than 500°C and PWR reactors do not exceed 300°C” adds Jean-Claude Garnier, a researcher at the CEA. Other reactor technologies are therefore to be considered to power these industrial processes. »
All over the world, engineers and physicists are probing the fantastic energy hidden in the atoms to invent a new generation of reactors. “This growing field of research is also a source of crucial fundamental advances in physics” adds Alexis Nuttin. The announcements are hence multiplying. Bluffs, or scientifically credible leads? we take stock of the three options that, in recent months, have made the most noise…
Thorium: now it’s serious
A year ago, in August 2021, China announced with great flourish that it had just completed the construction of a brand new 2 MW experimental reactor in Wuwei, near the Gobi Desert. No photo, no precise details on the architecture, it is just specified it is a thorium reactor.
This techno is a real mystery of the nuclear industry. Its principle: take a fuel in liquid form (here thorium) and dissolve it in a syrup of molten salts – fluoride or chloride. No uranium, no pressurized water: this alternative type of reactor avoids runaways, increases energy efficiency and reduces waste. By the 1960s, U.S. engineers at Oakridge National Laboratory had capitalized on these advantages and built two prototypes. But, ten years later, everything was put in the boxes, for lack of funding. The priority, at the time, was the uranium sector considered more promising.
Since then, research has (slowly) continued. “7 years ago, a clear revival of interest was expressed in the United States, and it was immediately copied by China which, as often in the nuclear sector, is on the same option as the Americans” describes Jean-Claude Garnier of the CEA. “In the labs, researchers have managed to show that the principle of this type of reactor works well” explains Daniel Heuer, who studies these molten salt reactors at IN2P3. “We must now do concrete engineering studies: this is what the Chinese will do”. The researcher points out, for example, the behaviour of fuel in salt, which is very difficult to simulate.
“Using thorium is also a challenge” adds Marat Margulis, a thorium expert at Bangor University in the UK. “There is no fissile isotope in nature for this element, a chain must be created and it is not won for commercial use”.
Will this time be the right one for thorium reactors? “I’ve been to China six times to see the work since 2011 and I feel like it’s really about to start” says Ritsuo Yoshioka, Japanese director of the International Thorium Forum. The United States and Canada are also on the list. But nothing should come to fruition before 2030 at the very least. “I expect from one week to the next the announcement of a first reaction maintained” predicts Jean-Claude Garnier (CEA). China has already announced its next goal: a 373 MW reactor within the next 7 years.
Hybrid: announcements and doubts
On September 9, 2022, China surprised everyone again. One of its top nuclear weapons researchers, Peng Xianjue, announced that a new hybrid fusion-fission reactor, of which he unveiled a functional diagram, was being studied in Chengdu, central China. The targeted schedule? A construction in 2025 before producing reactions as early as 2028 – which would be a world first.
The technology will not seek here to send the energy produced by fusion directly to the power grids. The goal is to collide hydrogen atoms to produce ultrafast neutrons, which will then hit the uranium of the fission reactor. Enough to initiate a reaction that will produce current in a subcritical way, that is to say without uncontrollable chain reaction. “In theory, this is correct, there will be no risk of runaway, but it will be necessary to check that there will not remain a residual power to evacuate and a real cooling capacity, in the event of an accident” says Annick Billebaud, a researcher at IN2P3 who is working on another type of hybrid reactor, aiming to transmute waste, with a particle accelerator instead of the fusion module.
China is not alone in exploring this option. Russian engineers, at the Kurchatov Institute in Moscow, announced in 2021 that they were developing a machine – the T-15MD (this Russian prototype will test the feasibility of a hybrid fusion/fission reactor in the coming years) – to study the possibility of one day using such a hybrid reactor.
“This principle is not new” says Ritsuo Yoshioka, a Japanese expert who has just written an article on this subject (not yet published): “Work led by the Russian Andrei Sakharov was ongoing as early as the 1950s, and at the end of the 1970s, the idea resurfaced again with the American Hans Bethe. Now the concept is coming back to China. Since fusion is an attractive but not credible solution for 50 or 60 years, the idea of using a system to produce just one primer is interesting, either to produce electricity or to incinerate nuclear waste”.
“Controlling fusion and fission at the same time seems unrealistic and smoky” says Alexis Nuttin. “I wonder if it’s not rather an excuse to hide other things, such as perhaps nuclear weapons tests” wonders Jérôme Bucalossi, an expert on fusion at the CEA. In the end, all the experts interviewed are cautious, even suspicious about this project and wait to have more details to see where this concept could lead us. Strangely, Peng Xianjue is now unreachable
Fusion: a real frenzy
Knocking two hydrogen nuclei to produce a heavier nucleus, and recovering the colossal amount of heat that emerges from it: never before has the quest for this carbon-free and waste-free energy been so frenetic.
On the one hand, there is a whole procession of reactors developed by major national institutions, which federate around ITER, a giant international laboratory located in Cadarache, France. The JET (Join European Torus), in Oxford, United Kingdom, produced last February 59 megajoules of energy for 5 seconds. And, a few weeks earlier, in China the EAST (Experimental Advanced superconducting Tokamak) announced that it had contained a plasma at 70 million degrees Celsius for more than 17 minutes. Two records. “All these tests show that the architectures chosen to contain the plasma are the right ones” comments Alain Bécoulet, ITER’s Director of Engineering.
Cadarache’s ITER is supposed to create its first plasma at the end of 2025. “The Iter schedule is likely to move” warns the engineer, “we had two technical problems in quick succession: a torus sector that did not have good flatness and a corrosion problem that occurred on our heat shield”. The expectations are all the greater because, alongside these institutional research centres, a new community is moving to attract investors. Like the German start-up Marvel Fusion, which raised 35 million euros last February 2022, or the Canadian company General Fusion, which announces a first demonstrator in 2025.
“Some of ITER’s technologies chosen more than 20 years ago are already a little outdated” points out Jérôme Bucalossi (CEA), “specific start-ups will, for example, test magnets with high-temperature superconductors that are able to hold more intense magnetic fields. These are real avenues for building future more compact and simpler reactors”. Will private companies defeat the pawn of institutional research? Alexis Nuttin at IN2P3 warns: “A nuclear industry takes 50 years, even a century to break through for reasons of development but also safety. Start-ups that report reactor construction in 10 or 20 years are blatantly lying”. “These experiments are useful to advance fusion in general, provided that we work in synergy,” says Alain Bécoulet. Dreams of fusion have not finished making sparks…
The fast neutron option: It’s advantage, after a plutonium primer, this so-called supergeneration technology consumes only the depleted uranium from the reactor waste. Three prototypes are already functional around the world (in Russia and China).
The high-temperature option: The fuel is here enclosed in ceramic balls, with high efficiency. China connected the first two mini-reactors to its grid a year ago. And two projects promise to be operational in the United States in 2030.
The supercritical water option: Its high pressure and temperature promise high yields. But, apart from some work in China for 8 years, this concept has never had a concrete declination. Corrosion, pressure resistance, chain reaction instabilities, the supercritical state remains poorly known in industrial installations.
The Z-pinch option: Here, it’s fusion: the idea developed by Zap Energy, a Seattle start-up, is to contain the plasma in the magnetic field it generates. Enough to reduce the reactors to the size of a house. However, the stability and durability of this beautiful concept is still largely to be proven.