An experiment to demonstrate the feasibility of nuclear fusion as a virtually inexhaustible, waste-free and non-polluting source of energy, ITER has already been 30-plus years in planning, with tens of billions invested. And if there are new fusion reactors designed based on research conducted here, they won’t be powering anything until the latter half of this century.
Speaking from Elysée Palace in Paris via an internet link during last month’s launch ceremony, President Emmanuel Macron said, “[ITER] is proof that what brings together people and nations is stronger than what pulls them apart. [It is] a promise of progress, and of confidence in science.” Indeed, as the COVID-19 pandemic continues to baffle modern science around the world, ITER is a welcome beacon of hope.
ITER comprises 35 collaborating countries, including members of the European Union, China, India, Japan, Russia, South Korea and the United States, which are directly contributing to the project either in cash or in kind with components and services. The EU has contributed about 45%, while the others pitch in about 9% each. The total cost of the project could be anywhere between $22 billion to $65 billion—even though the latter figure has been disputed.
The idea for ITER was sparked back in 1985, at the Geneva Superpower Summit, where President Ronald Reagan of the United States and General Secretary Mikhail Gorbachev of the Soviet Union spoke of an international collaboration to develop fusion energy. A year later, at the US–USSR Summit in Reykjavik, an agreement was reached between the European Union’s Euratom, Japan, the Soviet Union and the United States to jointly start work on the design of a fusion reactor. At that time, controlled release of fusion power hadn’t even been demonstrated—that only happened in 1991, by the Joint European Torus (JET) in the UK.
The first big component to be installed at ITER was the 1,250-metric ton cryostat base, which was lowered into the tokamak pit in late May 2020. The cryostat is India’s contribution to the reactor, and uses specialized tools specifically procured for ITER by the Korean Domestic Agency to place components weighing hundreds of tonnes and having positioning tolerances of a few millimeters. Machine assembly is scheduled to finish by the end of 2024, and by mid-2025, we are likely to see first plasma production.
Anil Bhardwaj, group leader of the cryostat team, tells IEEE Spectrum“First plasma will only verify [various] compliances for initial preparation of the plasma. That does not mean that we are achieving fusion.”
That will come another decade or so down the line.
If everything goes to plan, the first deuterium–tritium fusion experiments will be demonstrated by 2035, and will in essence be replicating the fusion reactions that take place in the sun. ITER estimates that for 50 MW of power injected into the tokamak to heat the plasma (up to 150 million degrees Celsius), 500 MW of thermal power for 400- to 600-second periods will be output, a tenfold return (expressed as Q ≥ 10). The existing record as of now is Q = 0.67, held by the JET tokamak.
Despite recent progress, there is still a lot of uncertainty around ITER. Critics decry the hyperbole around it, especially of it being a magic-bullet solution to the world’s energy problems, in the words of Daniel Jassby, a former researcher at the Princeton Plasma Physics Lab. His 2017 article explains why “scaling down the sun” may not be the ideal fallback plan.
“In the most feasible terrestrial fusion reaction [using deuterium–tritium fuel], 80% of the fusion output is in the form of barrages of neutron bullets, whose conversion to electrical energy is a dubious endeavor,” he said in an interview. Switching to a different type of reactor based on much weaker fusion reactions might result in less neutron production, but also are unlikely to produce net energy of any type.
Delays and mismanagement have also plagued ITER, something that Jassby contends was a result of poor leadership. “There are only a few people in the world who have the technological, administrative and political expertise that allow them to make continuous progress in directing and completing a multinational project,” he said. Bernard Bigot, who took over as director-general five years ago, possesses the requisite skillset, in Jassby’s opinion. At present, ITER is running about six years behind schedule.
Critics of ITER are also concerned about diverting resources from developing existing renewable energies. “The greatest energy issue of our time is not supply, but how to choose among the plethora of existing energy sources for wide-scale deployment,” Jassby said. ITER’s value, however, he said, lies in delinking the fantasy of electricity from fusion energy, thus saving hundreds of billions of dollars in the long run.
Jassby thinks that if successful, ITER will allow physicists to study long-lived, high-temperature fusioning plasmas or the development of neutron sources. There are practical applications for fusion neutrons, he says, such as isotope production, radiography and activation analysis. He adds that ITER can have significant benefits if new technologies emerge application in other fields, such as superconducting magnets, new materials and novel fabrication techniques.
Philippa Browning, professor of astrophysics at the University of Manchester, believes that only something of the scale of ITER can test how things work in fusion reactors. “It may well be that in future alternative devices turn out to be better, but those advantages could be incorporated into the successor to ITER which will be a demonstration fusion power station… The route to fusion power is slow, [so] we can hope that it will be ready when it is really needed in the second half of this century.” Meanwhile, she added, “it is important that other approaches to fusion are explored in parallel, smaller and more agile projects.”
One of the most impressive things about ITER, Browning said, is the combination of a truly international cooperation pushing at the frontiers in many ways. “Understanding how plasmas interact with magnetic fields is a hugely challenging scientific problem… There are all sorts of scientific and technological spin-offs, as well as the direct contribution to achieving, hopefully, a fusion power station.”
Nuclear fusion is hard to do. It requires extremely high densities and pressures to force the nuclei of elements like hydrogen and helium to overcome their natural inclination to repel each other. On Earth, fusion experiments typically require large, expensive equipment to pull off.
But researchers at NASA’s Glenn Research Center have now demonstrated a method of inducing nuclear fusion without building a massive stellarator or tokamak. In fact, all they needed was a bit of metal, some hydrogen, and an electron accelerator.
The team believes that their method, called lattice confinement fusion, could be a potential new power source for deep space missions. They have published their results in twopapers in Physical Review C.
“Lattice confinement” refers to the lattice structure formed by the atoms making up a piece of solid metal. The NASA group used samples of erbium and titanium for their experiments. Under high pressure, a sample was “loaded” with deuterium gas, an isotope of hydrogen with one proton and one neutron. The metal confines the deuterium nuclei, called deuterons, until it’s time for fusion.
“During the loading process, the metal lattice starts breaking apart in order to hold the deuterium gas,” says Theresa Benyo, an analytical physicist and nuclear diagnostics lead on the project. “The result is more like a powder.” At that point, the metal is ready for the next step: overcoming the mutual electrostatic repulsion between the positively-charged deuteron nuclei, the so-called Coulomb barrier.
To overcome that barrier requires a sequence of particle collisions. First, an electron accelerator speeds up and slams electrons into a nearby target made of tungsten. The collision between beam and target creates high-energy photons, just like in a conventional X-ray machine. The photons are focused and directed into the deuteron-loaded erbium or titanium sample. When a photon hits a deuteron within the metal, it splits it apart into an energetic proton and neutron. Then the neutron collides with another deuteron, accelerating it.
At the end of this process of collisions and interactions, you’re left with a deuteron that’s moving with enough energy to overcome the Coulomb barrier and fuse with another deuteron in the lattice.
Key to this process is an effect called electron screening, or the shielding effect. Even with very energetic deuterons hurtling around, the Coulomb barrier can still be enough to prevent fusion. But the lattice helps again. “The electrons in the metal lattice form a screen around the stationary deuteron,” says Benyo. The electrons’ negative charge shields the energetic deuteron from the repulsive effects of the target deuteron’s positive charge until the nuclei are very close, maximizing the amount of energy that can be used to fuse.
Aside from deuteron-deuteron fusion, the NASA group found evidence of what are known as Oppenheimer-Phillips stripping reactions. Sometimes, rather than fusing with another deuteron, the energetic deuteron would collide with one of lattice’s metal atoms, either creating an isotope or converting the atom to a new element. The team found that both fusion and stripping reactions produced useable energy.
“What we did was not cold fusion,” says Lawrence Forsley, a senior lead experimental physicist for the project. Cold fusion, the idea that fusion can occur at relatively low energies in room-temperature materials, is viewed with skepticism by the vast majority of physicists. Forsley stresses this is hot fusion, but “We’ve come up with a new way of driving it.”
“Lattice confinement fusion initially has lower temperatures and pressures” than something like a tokamak, says Benyo. But “where the actual deuteron-deuteron fusion takes place is in these very hot, energetic locations.” Benyo says that when she would handle samples after an experiment, they were very warm. That warmth is partially from the fusion, but the energetic photons initiating the process also contribute heat.
There’s still plenty of research to be done by the NASA team. Now they’ve demonstrated nuclear fusion, the next step is to create reactions that are more efficient and more numerous. When two deuterons fuse, they create either a proton and tritium (a hydrogen atom with two neutrons), or helium-3 and a neutron. In the latter case, that extra neutron can start the process over again, allowing two more deuterons to fuse. The team plans to experiment with ways to coax more consistent and sustained reactions in the metal.
Benyo says that the ultimate goal is still to be able to power a deep-space mission with lattice confinement fusion. Power, space, and weight are all at a premium on a spacecraft, and this method of fusion offers a potentially reliable source for craft operating in places where solar panels may not be useable, for example. And of course, what works in space could be used on Earth.
There are 53 nuclear reactors currently under construction around the world. Only two are in the United States, once the world’s leader in nuclear energy development. And those two reactors represent expansions of a preexisting two-reactor facility, Plant Vogtle in Waynesboro, Ga.
These two projects together represent the leading edge of commercial U.S. nuclear-fission reactor development today. The fact that there are only two raises questions about the direction of this once-booming energy sector. Is the United States redirecting its focus onto fusion and leaving fission behind? Or could a fission renaissance be yet to come?
Congress upped the U.S. Department of Energy’s nuclear fusion budget from US $564 million to $671 million for fiscal year 2020. And such companies as AGNI Energy in Washington state and Commonwealth Fusion Systems in Massachusetts (alongside Tokamak Energy and General Fusion in the United Kingdom and Canada, respectively) are courting venture capital for their multimillion-dollar visions of fusion’s bright future.
Meanwhile, in March, construction workers at the Vogtle fission plant hoisted a 680,000-kilogram steel-and-concrete structure to cap one of the containment vessels for the new AP1000 reactors. As John Kraft, a spokesperson for Georgia Power, explained, “The shield building is a unique feature of the AP1000 reactor design for Vogtle 3 and 4, providing an additional layer of safety around the containment vessel and nuclear reactor to protect the structure from any potential impacts.”
In 2005, the Nuclear Regulatory Commission (NRC) certified the AP1000 design, clearing the way for its sale and installation at these three sites more than a decade later. Last year, Dan Brouillette, the U.S. secretary of energy, wrote in a blog post: “The U.S. Department of Energy (DOE) is all in on new nuclear energy.”
NuScale’s modular design—with 12 smaller reactors, each operating at a projected 60 MW—met NRC Phase 4 approval at the end of last year. According to Diane Hughes, vice president of marketing and communications for NuScale, “This means that the technical review by the NRC is essentially complete and that the final design approval is expected on schedule by September 2020.”
The idea of harnessing multiple smaller reactors in a single design is not new, dating back as far as the 1940s. At the time, the economics of the smaller, modular design could not compete with bigger, individual reactors, says M.V. Ramana, a nuclear physicist and professor at the University of British Columbia’s School of Public Policy and Global Affairs.
“Nuclear power is unlike almost any other energy technology, in that it’s the one tech where the costs have gone up, not down, with experience,” he said. “The way to think about it is that the more experience we have with nuclear power, the more we learn about potential vulnerabilities that can lead to catastrophic accidents.”
However, Hughes of NuScale counters that, unlike the 54 competing small modular reactor designs that the IAEA has records of, NuScale is “the first ever small modular reactor technology to undergo…NRC design certification review.”
And in 2018, an interdisciplinary MIT report on nuclear energy found that NuScale’s reactor is “quite innovative in its design. It has virtually eliminated the need for active systems to accomplish safety functions, relying instead on a combination of passive systems and the inherent features of its geometry and materials.”
Of course, while the number of catastrophic nuclear accidents (such as Three Mile Island, Chernobyl, and Fukushima) is small for the amount of energy that nuclear power has generated over the past 70 years, Ramana adds, the cost of each accident is astronomical—sacrificing human lives and uprooting untold many more from disaster zones as well as requiring cleanups that cost hundreds of billions of dollars. “One every other decade is not good enough,” Ramana said.
This article appears in the June 2020 print issue as “Limited Progress for U.S. Nuclear.”
As my plane approaches the Tri-Cities Airport in south-central Washington state, the sandy expanse outside my window gives way to hundreds of bright green circles and squares. From this semi-arid terrain springs an irrigated oasis of potatoes, hops, peaches, and sweet corn. Just beyond our view is one of the most contaminated places in the world: the Hanford Site, home to 177 aging tanks of radioactive waste.
In “5 Big Ideas for Making Fusion Power a Reality,” I described how building a fusion reactor capable of producing electricity for the power grid may be engineering’s biggest challenge. But fusing atoms in home-built reactors is well within the reach of many amateur scientists. Indeed, it’s something of a trend. The website fusor.net, for example, lists hundreds of people who are active in this area.
Working in well-shielded basements and garages, most fusioneers are in it for their own edification. Carl Greninger, a data center manager at Microsoft, decided to take his project a step further. In 2010, he built a 60-kilovolt Farnsworth-Hirsch fusion reactor—commonly known as a fusor—in his Seattle-area basement.
A fusor consists of a spherical vacuum chamber surrounding a negatively charged spherical grid. When the reactor is fueled with deuterium and electrified, high-voltage current strips electrons off the deuterium atoms, converting them into positively charged atomic nuclei that fly toward the negatively charged inner cage. With the right combination of fuel, vacuum pressure, and voltage, some of the nuclei will collide violently enough for them to fuse together, releasing high-energy neutrons.
Unlike in a tokamak or a laser-fusion reactor, there is little hope of a fusor ever producing a breakeven reaction, where the energy output exceeds the energy input. Still, it’s a useful machine for running experiments that require neutrons and for learning about high-energy physics.
Shortly after he built his fusor, Greninger began inviting students in the area to come by and use it. To date, about 85 students have accepted his offer. After his workweek at Microsoft is done, he typically spends his Friday evenings with groups of students, who run experiments on the reactor or other high-tech equipment in what he calls the Northwest Nuclear Laboratories.
“Basically, I want to give them the chance to step into the persona of a scientist in a way they can’t at their schools,” says Greninger. “The experience is designed to inspire them, not necessarily to pour in a bunch more knowledge.”
And yet, some of his protégés have done impressive research. Collectively, the students have won more than US $660,000 in scholarships and other awards.
“Having that experience in high school led to a huge number of opportunities,” says Jake Hecla, who with two teammates developed an experiment that won second place in physics and astronomy at the International Science and Engineering Fair in 2013. The project, titled “Investigation of Anisotropic Neutron Radiation from a Farnsworth IEC Fusion Reactor,” revealed that in fusors with a geometry like Greninger’s, more fusion may take place in the walls than in the center well.
After graduating from high school, Hecla got a scholarship to MIT, where as a freshman he was awarded an elite research position based on his extensive experience working with high voltages. He’s now pursuing a Ph.D. in nuclear engineering at the University of California, Berkeley, where his research focuses on next-generation radiation detectors.
“Carl’s basement is where I developed the passion for the kinds of things I’m doing now,” Hecla says. “He gave us tools and direction and opportunities to pursue things we were curious about. For me, that has turned out to be an enormous advantage.”
The joke has been around almost as long as the dream: Nuclear fusion energy is 30 years away…and always will be. But now, more than 80 years after Australian physicist Mark Oliphant first observed deuterium atoms fusing and releasing dollops of energy, it may finally be time to update the punch line.
Over the past several years, more than two dozen research groups—impressively staffed and well-funded startups, university programs, and corporate projects—have achieved eye-opening advances in controlled nuclear fusion. They’re building fusion reactors based on radically different designs that challenge the two mainstream approaches, which use either a huge, doughnut-shaped magnetic vessel called a tokamak or enormously powerful lasers.
What’s more, some of these groups are predicting significant fusion milestones within the next five years, including reaching the breakeven point at which the energy produced surpasses the energy used to spark the reaction. That’s shockingly soon, considering that the mainstream projects pursuing the conventional tokamak and laser-based approaches have been laboring for decades and spent billions of dollars without achieving breakeven.
In Cambridge, Mass., MIT-affiliated researchers at Commonwealth Fusion Systems say their latest reactor design is on track to exceed breakeven by 2025. In the United Kingdom, a University of Oxford spin-off called First Light Fusion claims it will demonstrate breakeven in 2024. And in Southern California, the startup TAE Technologies has issued a breathtakingly ambitious five-year timeline for commercialization of its fusion reactor.
Irrational exuberance? Maybe. Fusion research is among the most costly of endeavors, depending on high inflows of cash just to pay a lab’s electricity bills. In the pursuit of funding, the temptation to overstate future achievements is strong. And past expectations of impending breakthroughs have repeatedly been dashed. What’s changed now is that advances in high-speed computing, materials science, and modeling and simulation are helping to topple once-recalcitrant technical hurdles, and significant amounts of money are flowing into the field.
Some of the new fusion projects are putting the newest generation of supercomputers to work to better understand and tweak the behavior of the ultrahigh-temperature plasma in which hydrogen nuclei fuse to form helium. Others have reopened promising lines of inquiry that were shelved decades ago. Still others are exploiting new superconductors or hybridizing the mainstream concepts.
Despite their powerful tools and creative approaches, many of these new ventures will fail. But if just one succeeds in building a reactor capable of producing electricity economically, it could fundamentally transform the course of human civilization. In a fusion reaction, a single gram of the hydrogen isotopes that are most commonly used could theoretically yield the same energy as 11 metric tons of coal, with helium as the only lasting by-product.
As climate change accelerates and demand for electricity soars, nuclear fusion promises a zero-carbon, low-waste baseload source of power, one that is relatively clean and comes with no risk of meltdowns or weaponization. This tantalizing possibility has kept the fusion dream alive for decades. Could one of these scrappy startups finally succeed in making fusion a practical reality?
Not so long ago, the outlook for fusion power was pretty bleak, with two of the biggest projects seemingly stalled. In 2016, the U.S. Department of Energy admitted that its US $3.5 billion National Ignition Facility (NIF) had failed to meet its goal of using lasers to “ignite” a self-sustaining fusion reaction. A DOE report suggested [PDF] that NIF’s research should shift from investigating laser-sparked ignition to determining whether such ignition is even possible.
The same year, the U.S. and several other governments began debating whether to pull their support from the International Thermonuclear Experimental Reactor (ITER). First proposed in 1985 and now under construction in southern France, ITER is the world’s biggest fusion experiment. It is a type of tokamak, which uses magnetic forces to confine and isolate the ferociously hot, energetic plasma needed to initiate and sustain fusion. But the project has been plagued by delays and cost overruns that have quintupled its original $5 billion price tag and pushed its projected completion date to 2035. (And even if it makes that date, it could be decades after that before commercial plants based on the design are in operation.) The setbacks and enormous expense of NIF and ITER had the effect of draining not just money but also enthusiasm from the field.
Even as the government-backed megaprojects foundered, alternative fusion-energy research began to gain momentum. The hope of those pursuing these new efforts is that their novel and smaller-scale approaches can accelerate past the decades-long incremental slog. Investors are finally taking notice and pouring money into the field. Over the past five years, private capitalists have injected about $1.5 billion into small-scale fusion-energy companies. Among those who have made significant bets on fusion are Amazon’s Jeff Bezos, Microsoft’s Bill Gates, and venture capitalist Peter Thiel. A few major corporations, including Lockheed Martin, have launched their own small-fusion projects.
Jesse Treu, a Ph.D. physicist who spent much of his career investing in biotech and med-tech startups, says he realized in 2016 that “wonderful things were starting to happen in fusion energy, but funding wasn’t catching up. It’s clear that private equity and venture capital are part of the solution to develop this technology, which is clearly the best energy answer for the planet.” He cofounded the Stellar Energy Foundation to connect fusion researchers with funding sources and to provide support and advocacy.
And public money has started to follow private: U.S. Department of Energy grant makers, who for decades funneled most nondefense fusion allocations to ITER, are now channeling some funding to projects at the fringes of mainstream research. The federal budget includes a $107 million increase for fusion projects in fiscal year 2020, including a research partnership program that allows small companies to conduct major experiments at the DOE’s national laboratories.
The U.S. government’s renewed interest stems in part from a perceived need to keep up with China, which recently restarted its fusion-energy program after a three-year moratorium. The Chinese government plans to switch on a new fusion reactor in Sichuan province this year. Meanwhile, the Chinese energy company ENN Energy Holdings has been investing in research programs abroad and is building a duplicate of Princeton Fusion Systems’ compact reactor in central China, with help from top U.S. scientists.
“Now that it’s looking like China will gobble up every idea the U.S. has failed to fund,” says Matthew J. Moynihan, a nuclear engineer and fusion consultant to investors, “that’s serving as a wake-up for the U.S. government.”
For all this activity and investment, fusion power remains as tough a problem as ever.
Unlike nuclear fission, in which a large, unstable nucleus is split into smaller elements, a fusion reaction occurs when the nuclei of a lightweight element, typically hydrogen, collide with enough force to fuse and form a heavier element. In the process, some of the mass is released and converted into energy, as laid out in Albert Einstein’s famous formula: E = mc2.
There’s an abundance of fusion energy in our universe—the sun and other stable stars are powered by thermonuclear fusion—but the task of triggering and controlling a self-sustaining fusion reaction and harnessing its power is arguably the most difficult engineering challenge humans have ever attempted.
To fuse hydrogen nuclei, earthbound reactor designers need to find ways to overcome the positively charged ions’ mutual repulsion—the Coulomb force—and get them close enough to bind via what’s known as the strong nuclear force. Most methods involve temperatures that are so high—several orders of magnitude hotter than the sun’s core temperature of 15 million °C—that matter can exist only in the plasma state, in which electrons break free of their atomic nuclei and circulate freely in gaslike clouds.
But a high-energy-density plasma is notoriously unstable and difficult to control. It wriggles and writhes and attempts to break free, migrating to the edges of the field that contains it, where it quickly cools and dissipates. Most of the challenges surrounding fusion energy center around plasma: how to heat it, how to contain it, how to shape it and control it. The two mainstream approaches are magnetic confinement and inertial confinement. Magnetic-confinement reactors such as ITER attempt to hold the plasma steady within a tokamak, by means of powerful magnetic fields. Inertial-confinement approaches, such as NIF’s, generally use lasers to compress and implode the plasma so quickly that it’s held in place long enough for the reaction to get going.
Scientists have long thought that bigger is better when it comes to creating stable and energy-dense plasma fields. But with recent advances in supercomputing and complex modeling, researchers are unraveling more of the mysteries underlying plasma behavior and developing new tricks for handling it without huge, complex machinery.
Among the researchers at the forefront of this work is physicist C. Wendell Horton Jr. of the University of Texas Institute of Fusion Studies. He uses the university’s Stampede supercomputer to build simulations of plasma flow and turbulence inside magnetic-confinement reactors. “We’re making calculations that were impossible just a few years ago and modeling data about plasma in three dimensions and in time,” Horton says. “Now we can see what’s happening with much more nuance and detail than we would get with analytic theories and even the most advanced probes and diagnostic measurements. That’s giving us a more holistic picture of what’s needed to improve reactor design.”
Horton’s findings have informed the design of large-scale experiments such as ITER, as well as small-scale projects. “The problem with ITER is that no matter how well they get the plasma to behave, they haven’t figured out how to get the reaction to self-sustain,” he says. “It’s still going to burn out in a matter of minutes, and that’s obviously not solving the energy problem.” He and other researchers believe that some of the small-scale efforts are much closer to achieving a steady-state reaction that could generate baseload electricity.
Among the most mature of the fusion startups is California-based TAE Technologies (formerly Tri Alpha Energy), which launched in 1998.
The TAE reactor is designed to make use of what’s called a field-reversed configuration (FRC) to create a swirling ring of plasma that contains itself in its own magnetic field. (Princeton Fusion Systems’ design is also an FRC.) Instead of using deuterium and tritium—the hydrogen-isotope blend that fuels most fusion reactors—the TAE reactor injects beams of high-energy neutral hydrogen particles into hydrogen-boron fuel, forcing a reaction that produces alpha particles (ionized helium nuclei). Heat generated in the containment vessel caused by the deposit of soft X-ray energy will be converted into electricity using a conventional thermal conversion system, which heats water into steam to drive a turbine.
Hydrogen-boron fusion is aneutronic, meaning that the primary reaction does not produce damaging neutron radiation. The drawback is that burning the fuel requires extraordinary temperatures, as high as 3 billion °C. “When you’re that hot, the electrons are radiating like crazy,” says William Dorland, a physics professor at the University of Maryland. “They’re going to cool off the plasma faster than you can heat it.” Although FRC machines seem to be less prone to plasma instabilities than some other magnetic-confinement methods, no one has yet demonstrated an FRC reactor that can create a stable plasma.
TAE cofounder and CEO Michl Binderbauer says the company’s latest machine, dubbed Norman (in honor of company cofounder Norman Rostoker), is achieving “significant improvements in plasma containment and stability over the previous-generation machine.” What’s driving the improvements are advances in artificial intelligence and machine learning, enabled by a cutting-edge algorithm developed by Google called Optometrist. TAE adapted the algorithm in partnership with Google to analyze the plasma-behavior data and home in on the combination of variables that will create the most ideal conditions for fusion. The researchers described it in a Nature paper published in 2017.
“We’re doing things we could have never done 10 years ago, and that’s driving faster and faster cycles of learning,” says Binderbauer.
Advanced computing is also breathing new life into promising lines of inquiry that were abandoned years ago due to budget cuts or technical roadblocks. General Fusion, based near Vancouver, was founded by Canadian plasma physicist Michel Laberge. He quit a lucrative job developing laser printers to pursue an approach called magnetized target fusion (MTF). The company has attracted more than $200 million, including investments from Jeff Bezos and the governments of Canada and Malaysia.
General Fusion’s design combines features of magnetic-confinement and inertial-confinement fusion. It injects pulses of magnetically confined plasma fuel into a sphere filled with a vortex of molten lead and lithium. Pistons surrounding the reactor drive shock waves toward the center, compressing the fuel and forcing the particles into a fusion reaction. The resulting heat is absorbed in the liquid metal and used to produce steam to spin a turbine and generate electricity.
“You can think of it in some ways as the opposite of a tokamak,” says Laberge. “Tokamaks work with a big plasma field that’s [relatively] low density. We’re trying to make a mini-size plasma that’s extremely high density, by squashing it in with the shock waves. Because the field is so dense and small, we only need to keep it together for a millisecond for it to react.”
In the 1970s, the U.S. Naval Research Laboratory experimented with a piston system to trigger nuclear fusion. Those experiments failed, due in large part to an inability to precisely control the timing of the shock waves. Laberge’s team has developed advanced algorithms and highly precise control systems to fine-tune the speed and timing of the shock waves and compression.
“In those experiments in the 1970s, the problem was symmetry,” says Laberge. “We’ve now achieved the accuracy and force we need, so that part’s solved.”
Using liquid metal could solve another of fusion energy’s primary challenges: Neutron radiation erodes a reactor’s walls, which must be replaced frequently and disposed of as low-level radioactive waste. The liquid metal protects the solid outer wall from damage. There’s some irradiation of the liquid metal, but there’s no need to regularly replace it, and so the reactor doesn’t produce a steady stream of low-level waste.
General Fusion’s newest reactor, which generated plasma for the first time in late 2018, is the centerpiece of a facility that Laberge says will demonstrate an end-to-end capability to produce electricity from nuclear fusion. “Now that we’ve successfully created a stable, long-lived plasma, we can see that we have a viable path toward having the plasma generate more energy than it consumes,” he says. “In terms of commercialization, our timeline is now a matter of years, not decades.”
Virginia-based HyperJet Fusion Corp. has an approach similar to General Fusion’s, but instead of pistons, some 600 plasma guns fire jets of plasma into the reactor. The merging of the jets forms a plasma shell, or liner, which then implodes and ignites a magnetized target plasma. The system doesn’t need a heating system to bring the fuel to fusion temperatures, says HyperJet CEO and chief scientist F. Douglas Witherspoon. “The imploding plasma liner contains the target plasma and provides the energy to elevate the temperature to fusion conditions. And because we’re using a much higher-density plasma than a magnetic-confinement system would, it reduces the size of the fusing plasma from meter scale to centimeter scale.”
Witherspoon says the advantage of the HyperJet approach over tokamaks is that it doesn’t require expensive superconducting magnets to generate the enormous magnetic fields needed to confine the fusion-burning plasma.
Tokamaks themselves are also getting a reboot, thanks to the use of different superconducting materials that could make magnetic confinement more viable. MIT spin-off Commonwealth Fusion Systems is employing yttrium-barium-copper oxide (YBCO), a high-temperature superconductor, in the magnets on its Sparc reactor.
Commonwealth cofounder Martin Greenwald, who is also the deputy director of MIT’s Plasma Science and Fusion Center, calculates that the Sparc reactor’s YBCO magnets will be able to generate a field of about 21 teslas at their surface and 12 T at the center of the plasma, roughly doubling the field strength of tokamak magnets made of niobium-tin. Stronger magnetic fields produce a stronger confining force on the charged particles in the plasma, improving insulation and enabling a much smaller, cheaper, and potentially better performing fusion device.
“If you can double the magnetic field and cut the size of the device in half, with identical performance, that will be a game changer,” Greenwald says.
Indeed, one advantage of the newer, small-scale fusion projects is that they can concentrate on the novel aspects of their designs, while taking advantage of decades of hard-won knowledge about the fundamentals of fusion science. As Greenwald puts it, “We think we can get to commercial deployment of fusion power plants faster by accepting the conventional physics basis developed around the ITER experiment and focusing on our collaborations between physicists and magnet engineers who have been setting records for decades.”
Some promising startups, though, aren’t content to accept the conventional wisdom, and they’re tackling the underlying physics of fusion in new ways. One of the more radical approaches is that of First Light Fusion. The British company intends to produce fusion using an inertial-confinement reactor design inspired by a very noisy crustacean.
The pistol shrimp’s defining feature is its oversize pistol-like claw, which it uses to stun prey. After drawing back the “hammer” part of its claw, the shrimp snaps it against the opposite side of the claw, creating a rapid pressure change that produces vapor-filled voids in the water called cavitation bubbles. As these bubbles collapse, shock waves pulse through the water at 25 meters per second, enough to take out small marine animals.
“The shrimp just wants to use the pressure wave to stun its prey,” says Nicholas Hawker, First Light’s cofounder and CEO. “It doesn’t care that as the cavity implodes, the vapor inside is compressed so forcefully that it causes plasma to form—or that it has created the Earth’s only example of inertial-confinement fusion.” The plasma reaches temperatures of over 4,700 °C, and it creates a 218-decibel bang.
Hawker focused on the pistol shrimp’s extraordinary claw in his doctoral dissertation at the University of Oxford, and he began studying whether it might be possible to mimic and scale up the shrimp’s physiology to spark a fusion reaction that could produce electricity.
After raising £25 million (about $33 million) and teaming up with international engineering group Mott MacDonald, First Light is building an ICF reactor in which the “claw” consists of a metal disk-shaped projectile and a cube with a cavity filled with deuterium-tritium fuel. The projectile’s impact creates shock waves, which produce cavitation bubbles in the fuel. As the bubbles collapse, the fuel within them is compressed long enough and forcefully enough to fuse.
Hawker says First Light hopes to initiate its first fusion reaction this year and to demonstrate net energy gain by 2024. But he acknowledges that those achievements won’t be enough. “Fusion energy doesn’t just need to be scientifically feasible,” he says. “It needs to be commercially viable.”
No one believes it will be easy, but the extraordinary challenge of fusion energy—not to mention the pressing need—is part of the attraction for the many scientists and engineers who’ve recently been drawn to the field. And increasingly, they have the resources to finance their work.
“This notion that you hear about fusion being another 30 or 40 or 50 years away is wrong,” says TAE’s Binderbauer, whose company has raised more than $600 million. “We’re going to see commercialization of this technology in time frames of a half decade.”
Veteran fusion researchers such as Dorland and Horton tend to have a more tempered outlook. They worry that grand promises that fall short may undercut public and investor support, as has happened in the past. Any claims of commercialization within the decade “are just not true,” says Dorland. “We’re still a lot more than one breakthrough away from having a pathway to fusion power.”
What few will argue with, though, is the dire need for nuclear fusion in the near future.
“I think it’s not going too far to say that fusion is having its Kitty Hawk moment,” says MIT’s Greenwald. “We don’t have a 747 jet, but we’re flying.”
This article appears in the February 2020 print issue as “5 Big Ideas for Fusion Power.”
About the Author
Tom Clynes is a freelance writer and photojournalist who covers science and environmental issues. His 2015 book The Boy Who Played With Fusion (Houghton Mifflin Harcourt) tells the unlikely tale of a 14-year-old who became the youngest person to build a working fusion reactor.
The world’s first floating nuclear power plant (FNPP) docked at Pevek, Chukotka, in Russia’s remote Far East on 14 September. It completed a journey of some 9,000 kilometers from where it was constructed in a St. Petersburg shipyard. First, it was towed to the city of Murmansk, where its nuclear fuel was loaded, and from there took the North Sea Route to the other side of Russia’s Arctic coast.
The co-generation plant, named the Akademik Lomonosov, consists of a non-motorized barge, two pressurized-water KLT-40S reactors similar to those powering Russian nuclear icebreakers, and two steam turbine plants.
The FNPP can generate up to 70 megawatts (MW) of electricity and 50 gigacalories of heat an hour. That is sufficient to power the electric grids of the resource-rich region—where some 50,000 people live and work—and also deliver steam heat to the supply lines of Pevek city. The plant will manage this second feat by using steam extracted from the turbines to heat its intermediate circuit water system, which circulates between the reactor units and the coastal facilities, from 70 to 130degrees C.
Construction of the floating reactor began in 2007 and had to overcome a messy financial situation including the threat of bankruptcy in 2011. The venture is based on the small modular reactor (SMR) design: a type of nuclear fission reactor that is smaller than conventional reactors. Such reactors can be built from start to finish at a plant and then shipped—fully-assembled, tested, and ready to operate—to remote sites where normal construction would be difficult to manage.
Andrey Zolotkov, head of the Murmansk, Russia office of Bellona Foundation, an environmental organization based in Oslo, Norway, acknowledges the practicability of the SMR design. But he is one of many who questions its necessity in this particular case.
“The same plant could be built on the ground there (in Chukotka) without resorting to creating a floating structure,” says Zolotkov. “After all, the [nuclear power plant] presently in use was built on land there and has been operating for decades.”
The floating design has raised both environmental and safety concerns, given that the plant will operate in the pristine Arctic and must endure its harsh winters and choppy seas. Greenpeace has dubbed it a “floating Chernobyl,” and “a nuclear Titanic.”
Coastal structures, dams, and breakwaters have also been built to protect the vessel against tsunamis and icebergs.
The plant employs a number of active and passive safety systems, including an electrically-driven automated system and a passive system that uses gravity to insert control rods into the reactor core to ensure the reactor remains at subcritical levels in emergencies. The reactors also use low enriched uranium in a concentration below 20 percent of Uranium-235. This makes the fuel unsuitable for producing nuclear weapons.
Given such safety measures, Rosatom says on its site that a peer-reviewed probabilistic safety assessment modeling of possible damage to the FNPP finds the chances of a serious accident happening at the FNPP “are less than one hundred thousandth of a percent.”
Zolotkov, who worked in various capacities—including radiation safety officer—for 35 years in Russia’s civilian nuclear fleet, also notes that there have been no serious incidents on such ships since 1975. “In the event of an accident in the FNPP, the consequences, I believe, would be localized within its structure, so the release of radioactive substances will be minimal,” he says.
The plant’s nuclear fuel has to be replaced every three years. The unloaded fuel is held in onboard storage pools, and later in dry containers also kept on board. Every 10 to 12 years during its 40-year life cycle (possibly extendable to 50 years), the FNPP will be towed to a special facility for maintenance.
After decommissioning, the plant will be towed to a deconstruction and recycling facility. Rosatom says on its site, “No spent nuclear fuel or radioactive waste is planned to be left in the Arctic—spent fuel will be taken to the special storage facilities in mainland Russia.”
Rosatom has not disclosed the cost of the venture, calling it a pilot project. It is currently working on a next-generation version that will use two RITM-200M reactors, each rated at 50 MW. Improvement targets include a more compact design, longer periods between refueling, flexible load-following capabilities, and multipurpose uses that include water desalination and district heating.
Provided Rosatom receives sufficient orders, it says it aims to compete in price with plants based on fossil fuels and renewable energy.
The company, however, may face challenges other than marketing and operating its novel design. “These FNPPs will eventually carry spent nuclear fuel and are not yet recognized by international maritime law,” says Zolotkov. “So Rosatom may face problems obtaining permits and insurance when it comes to towing them along certain sea routes.”
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