The UK government has spurned an invitation to become an official member of the ITER nuclear fusion experiment, having lost access to the project following Brexit. Instead, the government plans to focus on UK-based fusion efforts, both public and private.

ITER, the world’s largest fusion experiment, is under construction in France and is expected to be completed in 2025 after many delays. The project is being funded by a huge international collaboration including China, India, Japan, Russia, South Korea, the US and the European Union. The UK did have access through the EU, but since Brexit has fallen outside ITER. Negotiations with the EU have since seen announcements that the UK would rejoin Horizon Europe, a joint scientific research effort, but not Euratom, which focuses on nuclear power.

The head of Euratom Research, Elena Righi, seemingly called for the UK to officially rejoin the ITER experiment this week, but the UK government has said it stands by its decision to step down and believes private sector investment in fusion research will be a more efficient and cost-effective path to commercial reactors.

Righi was speaking at an event in Oxfordshire to celebrate the achievements of the JET fusion reactor which was permanently shut down late last year and will now be decommissioned.

“The Commission and the Council of the EU, in a joint statement, noted with regret that the United Kingdom decided not to associate to the Euratom programme and the Fusion for Energy joint undertaking,” said Righi. “For the next period starting in 2028 the EU institutions called emphatically [for] the UK to participate in all the four programmes [ITER plus the EC’s three other large scale fusion research projects].”

“This will allow a truly European fusion community to continue its integrated efforts and to resolve the current ambiguous participation of the UKAEA to EUROfusion and enable the UK’s fuller integration in the construction and operation eventually of ITER.”

New Scientist asked the European Commission to clarify Righi’s statement, but received no response.

At the same event Andrew Bowie, the UK minister responsible for nuclear energy, told New Scientist that the UK stands by its decision not to rejoin the effort, as doing so freed up £650 million which can be instead used to fund a mix of private and public research.

“For all the experiments, for all the research, for all great work here at JET, the ultimate aim of all of this is to get fusion onto the grid, generating power into homes and businesses,” says Bowie. “To make it a commercial reality, to bring the power of the sun into peoples’ homes, we’re going to need significant buy-in from the private sector as well.”

“The decision not to reassociate was the right one. We had here in the UK moved to such a place that reassociating would divert, we believe, time and resource, and money, away from where we wanted to take our fusion projects. It’s not that there was an ideological decision not to reassociate, it was a practical decision,” says Bowie.

Bowie says that the UK can get more bang for its buck from private sector investment, but is “very open” to finding new ways of working with ITER such as personnel exchanges. “We’re not saying no to working with ITER,” says Bowie, who explicitly ruled out an official re-entry to the ITER project: “We stand by that decision.”

The UK is also developing plans for a Spherical Tokamak for Energy Production (STEP), a nuclear fusion power station, which it hopes will create plasma by 2035 and reach net energy gain, where more power is created than input, five years later. It announced the £650m budget late last year, some of which will be set aside for STEP, to invest in a range of public and private fusion research projects.

Juan Matthews at the University of Manchester’s Dalton Nuclear Institute says that spherical reactors like STEP, if successful, offer the promise of smaller and cheaper fusion power than with large designs like ITER, which is experiencing its own problems.

“It’s continually being delayed,” says Matthews. “It’s got the big project syndrome where things are just not coming in on time and costs are going up. The STEP initiative, and losing contact with ITER, could be an impetus which would result in [the UK] demonstrating power generation earlier than Europe. I’m very optimistic about the use of spherical tokamaks.”

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• nuclear fusion technology

The UK’s 40-year-old fusion reactor achieved a world record for energy output in its final runs before being shut down for good, scientists have announced.

The Joint European Torus (JET) in Oxfordshire began operating in 1983. When running, it was temporarily the hottest point in the solar system, reaching 150 million°C.

The reactor’s previous record was a reaction lasting for 5 seconds in 2021, producing 59 megajoules of heat energy. But in its final tests in late 2023, it surpassed this by sustaining a reaction for 5.2 seconds while also reaching 69 megajoules of output, using just 0.2 milligrams of fuel.

This equates to a power output of 12.5 megawatts – enough to power 12,000 homes, said Mikhail Maslov of the UK Atomic Energy Agency at a press conference on 8 February.

Today’s nuclear power plants rely on fission reactions, where atoms are smashed apart to release energy and smaller particles. Fusion works in reverse, squeezing smaller particles together into larger atoms.

Fusion can create more energy with none of the resulting radioactive waste created by fission, but we don’t yet have a practical way to harness this process in a power plant.

JET forged together atoms of deuterium and tritium – two stable isotopes of hydrogen – in plasma to create helium, while also releasing a vast amount of energy. This is the same reaction that powers our sun. It was a type of fusion reactor known as a tokamak, which contains plasma in a donut shape using rings of electromagnets.

Scientists ran the last experiments with deuterium-tritium fuel at JET in October last year and other experiments continued until December. But the machine has now been shut down for good and it is being decommissioned over the next 16 years.

Juan Matthews at the University of Manchester, UK, says JET will reveal many secrets as it is dismantled, such as how the lining of the reactor deteriorated through contact with plasma and where valuable tritium – worth around £30,000 a gram – has embedded in the machinery and can be recovered. This will be vital information for future research and commercial reactors.

“It’s great that it’s gone out with a little flourish,” says Matthews. “It’s got a noble history. It’s served its time and they’re going to squeeze a bit more information out of it during its decommissioning period as well. So it’s not something to be sad about; it’s something to be celebrated.”

A larger and more modern replacement for JET, the International Thermonuclear Experimental Reactor (ITER) in France, is nearing completion and its first experiments are due to start in 2025.

Tim Luce, deputy head of the ITER construction project, told the press conference that ITER will scale up the energy output to 500 megawatts, or possibly even 700.

“These are what I usually call power plant scale,” he said. “They’re at the lower end of what you would need for an electricity generating facility. In addition, we need to extend the timescale to at least 300 seconds for the high fusion power and gain but perhaps as long as an hour in terms of energy production. So what JET has done is exactly a scale model of what we have to do in the ITER project.”

Another reactor using the same design, the Korea Superconducting Tokamak Advanced Research (KSTAR) device, recently managed to sustain a reaction for 30 seconds at temperatures in excess of 100 million°C.

There are other approaches to creating a working fusion reactor being pursued around the world as well, such as the National Ignition Facility at Lawrence Livermore National Laboratory in California. This bombards capsules of fuel with immensely powerful lasers, a process called inertial confinement fusion, and has managed to unleash almost twice the energy that was put into it.

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The UK’s 40-year-old fusion reactor smashed its own record for both reaction duration and energy output in its final runs before being shut down for good, scientists have announced.

The Joint European Torus (JET) in Oxfordshire began operating in 1983. When running, it was temporarily the hottest point in the solar system, reaching 150 million°C.

The reactor’s previous record was a reaction lasting for 5 seconds in 2o21, producing 59 megajoules of heat energy. But in its final tests in late 2023, it surpassed this by sustaining a reaction for 5.2 seconds while also reaching 69 megajoules of output, using just 0.2 milligrams of fuel. This amount of energy is roughly equivalent to the electricity consumed by an average person in the UK in a single day.

Today’s nuclear power plants rely on fission reactions, where atoms are smashed apart to release energy and smaller particles. Fusion works in reverse, squeezing smaller particles together into larger atoms.

Fusion can create more energy with none of the resulting radioactive waste created by fission, but we don’t yet have a practical way to harness this process in a power plant.

JET forged together atoms of deuterium and tritium – two stable isotopes of hydrogen – in plasma to create helium, while also releasing a vast amount of energy. This is the same reaction that powers our sun. It was a type of fusion reactor known as a tokamak, which contains plasma in a donut shape using rings of electromagnets.

Scientists ran the last experiments with deuterium-tritium fuel at JET in October last year and other experiments continued until December. But the machine has now been shut down for good and it is being decommissioned over the next 16 years.

Juan Matthews at the University of Manchester, UK, says JET will reveal many secrets as it is dismantled, such as how the lining of the reactor deteriorated through contact with plasma and where valuable tritium – worth around £30,000 a gram – has embedded in the machinery and can be recovered. This will be vital information for future research and commercial reactors.

“It’s great that it’s gone out with a little flourish,” says Matthews. “It’s got a noble history. It’s served its time and they’re going to squeeze a bit more information out of it during its decommissioning period as well. So it’s not something to be sad about; it’s something to be celebrated.”

A larger and more modern replacement for JET, the International Thermonuclear Experimental Reactor (ITER) in France, is nearing completion and its first experiments are due to start in 2025. Another reactor using the same design, the Korea Superconducting Tokamak Advanced Research (KSTAR) device, recently managed to sustain a reaction for 30 seconds at temperatures in excess of 100 million°C.

There are other approaches to creating a working fusion reactor being pursued around the world as well, such as the National Ignition Facility at Lawrence Livermore National Laboratory in California. This bombards capsules of fuel with immensely powerful lasers, a process called inertial confinement fusion, and has managed to unleash almost twice the energy that was put into it.

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Scientists have confirmed that a fusion reaction in 2022 reached a historic milestone by unleashing more energy than was put into it – and subsequent trials have produced even better results, they say. The findings, now published in a series of papers, give encouragement that fusion reactors will one day create clean, plentiful energy.

Today’s nuclear power plants rely on fission reactions, where atoms are smashed apart to release energy and smaller particles. Fusion works in reverse, squeezing smaller particles together into larger atoms; the same process powers our sun.

Fusion can create more energy with none of the radioactive waste involved in fission, but finding a way to contain and control this process, let alone extract energy from it, has eluded scientists and engineers for decades.

Experiments to do this using capsules of deuterium and tritium fuel bombarded with lasers – a process called inertial confinement fusion (ICF) – began at the Lawrence Livermore National Laboratory (LLNL) in California in 2011. The energy released was initially only a tiny fraction of the laser energy put in, but it gradually increased until an experiment on 5 December 2022 finally passed the crucial milestone of breaking even. That reaction put out 1.5 times the laser energy required to kickstart it.

In one paper, the lab’s National Ignition Facility (NIF) claims that trial runs since then have yielded even greater ratios, peaking at 1.9 times the energy input on 4 September 2023.

Richard Town at LLNL says the team’s checks and double-checks since the 2022 result have proved that it “wasn’t a flash in the pan”, and he believes there is still room for improvement.

Even with the hardware currently installed at NIF, Town says it is likely that yields could be improved, but if the lasers can be upgraded – which would take years – things could be pushed even further. “A bigger hammer always helps,” he says. “If we can get a bigger hammer, I think we could get to target gains of about roughly 10.”

But Town points out that NIF was never built to be a prototype reactor and isn’t optimised for boosting yields. Its main job is to provide critical research for the US nuclear weapons programme.

Part of this work involves exposing electronics and payloads from nuclear bombs to the neutron bombardment that takes place when ICF reactions occur, to check that they will function in the event of all-out nuclear war. The danger of an electronics failure was highlighted during a test in 2021 when NIF fired and wiped out all lights across the site, plunging researchers into darkness. “Those lights were not hardened, but you can sort of imagine a military component that has to survive a much higher dosage,” says Town.

This mission means some research from the project remains classified; even the concept of ICF was a classified secret into the 1990s, says Town.

The announcement that ICF had reached the break-even point in 2022 provided hope that fusion power was drawing closer, and this will be bolstered by news that further progress has been made. But there are caveats.

Firstly, the energy output falls far short of what would be needed for a commercial reactor, barely creating enough to heat a bath. Worse than that, the ratio is calculated using the lasers’ output, but to create that 2.1 megajoules of energy, the lasers draw 500 trillion watts, which is more power than the output of the entire US national grid. So these experiments break even in a very narrow sense of the term.

Martin Freer at the University of Birmingham, UK, says these results are certainly not an indication that practical fusion reactors can now be built. “There’s still science to be done,” he says. “It’s not like we know the answers to all of this and we don’t need researchers any more.”

Freer says that as scientific experiments progress, they throw up engineering challenges to create better materials and processes, which will allow better experiments and more progress. “There is a chance that we will have fusion,” he says. “But the challenges that we have are pretty steep, scientifically.”

Aneeqa Khan at the University of Manchester, UK, agrees that recent progress in fusion research is positive, but stresses that it will be decades before commercial power plants are operational – and even that will hinge on global collaboration and a concerted effort to train more people in the field. She warns against interpreting progress in fusion research as a possible solution to tackle our reliance on energy from fossil fuels.

“Fusion is already too late to deal with the climate crisis. We are already facing the devastation from climate change on a global scale,” says Khan. “In the short term, we need to use existing low-carbon technologies such as fission and renewables, while investing in fusion for the long term, to be part of a diverse low-carbon energy mix. We need to be throwing everything we have at the climate crisis.”

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• nuclear energy/
• fusion power

The first useful application of fusion reactors may be to create radioactive isotopes for cancer treatment or medical imaging rather than to generate energy, claims a UK start-up firm.

Scientists and engineers have worked on building a fusion reactor for a century, and a practical fusion power station is still thought to be decades away.

But Astral Systems is working on tiny fusion reactors that don’t attempt to generate large amounts of power, or even to equal the amount of …

Earlier this year, the Joint European Torus (JET) turned 40. JET is a fusion energy tokamak device based in Oxfordshire, UK, operated by the UK Atomic Energy Authority. When powered up, plasma rushes around the reactor’s core at 150 million°C, hotter than the centre of the sun.

After decades of research, JET is set to close. But as we discovered on a recent visit, the reactor has made huge steps forward for fusion power, paving the way for the next generation of reactors.

JET is the only fusion machine able to operate with tritium within its fuel mix, and has provided valuable experimental data for the International Thermonuclear Experimental Reactor (ITER), a next-generation tokamak currently under construction near Marseilles, France. The aim is that ITER will produce 10 times more energy than what is put into it, and it could bring us closer to the promise of a clean, unlimited energy source. Join Alex Wilkins as he explores JET and gets insights into the future of fusion.

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A breakthrough fusion experiment has produced a net gain in energy for only the second time ever and with improved performance over the first successful attempt. But before you get excited about the coming era of unlimited clean energy, there are some important caveats to keep in mind.

What’s so good about fusion power?

Today’s nuclear power plants rely on fission reactions, where atoms are smashed apart to release energy and smaller particles. Fusion works differently, by squeezing smaller particles together into larger atoms – the same process that operates within our sun. Fusion can create more energy, with no radioactive waste, but containing and controlling such a reaction has proven to be a monumental problem for both physicists and engineers.

What has happened and what is ignition?

In December 2022, researchers at the Lawrence Livermore National Laboratory (LLNL) in California reached a historic milestone: they got more energy out of a fusion reaction than they put in. The lab’s National Ignition Facility (NIF) fusion reactor used lasers to create enough heat and pressure to turn deuterium and tritium – isotopes of hydrogen – into a plasma in which fusion could occur. These lasers output 2.1 megajoules of energy, but the reactor produced about 2.5 megajoules, roughly a 20 per cent increase. While those numbers are nowhere near the sort of ratio you would need to run a commercial reactor, it offered a vital glimmer of hope that fusion reactors were a viable goal.

Now the lab has reportedly created a second ignition – the term for a reaction that surpasses break-even – and improved on those numbers with the reactor producing around 3.5 megajoules. The experiment occurred on 30 July, according to a report in the Financial Times.

Does this mean fusion power has been solved?

In short, no.

One problem is that while the reactor’s output is higher than the laser’s output, the lasers themselves are very inefficient. To create 2.1 megajoules of energy they draw 500 trillion watts, which is more power than the output of the entire US national grid. So a significant challenge for the future is to create a reaction that breaks even with its total energy requirements, and not just the final laser stage.

Another issue is that the NIF reactor can fire only once, for a few billionths of a second, before it has to spend several hours cooling its components in order to be switched on once more. A commercial reactor would have to run nearly continuously with multiple ignitions a second.

And, of course, even once a reactor can run for long periods and offset its true energy requirements by the lasers, it would still only be breaking even. For fusion to become a viable alternative to existing power sources, we must be able to extract a large amount of net energy – enough to make the enormous cost of building it worthwhile.

Will fusion be solved in the future?

While it is still impossible to tell for sure, as there could be insurmountable problems ahead, there is more cause for optimism than ever before. The ignition milestone effectively proves that the science is sound, and makes the problem one of engineering rather than physics.

There are two main research approaches aiming to achieve viable nuclear fusion. One uses magnetic fields to contain a plasma, while the other uses lasers. NIF uses the second approach, known as inertial confinement fusion, where a tiny capsule containing hydrogen fuel is blasted with lasers, causing it to heat up and rapidly expand. But there are a host of startups working on unusual designs that all have the potential to break through. All these experiments are helping us to better understand the problem, and the best way forward.

But one thing is clear: with a working fusion reactor still many years away at the very least, we cannot rely on the technology to solve the climate change crisis. Fusion reactors will be perhaps the greatest pay-off ever received from a coordinated research effort stretching back more than a century, but clean and abundant energy will have to come from renewable sources for the short and medium term.

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Update: Nuclear fusion researchers have achieved historic energy milestone

A controlled fusion reaction has generated more energy than was put into the system for the first time, bringing viable fusion power another step closer to reality

For the first time on Earth, a controlled fusion reaction has generated more power than it requires to run, researchers have confirmed. The experiment is a major step towards commercial fusion power, but experts say there is still a vast engineering effort needed to increase efficiency and reduce cost.

Rumours of the experiment at Lawrence Livermore National Laboratory (LLNL) in California emerged on 11 December, but the news has been formally announced in a press conference today. In an experiment on 5 December, the lab’s National Ignition Facility (NIF) fusion reactor generated a power output of 3.15 megajoules from a laser power output of 2.05 megajoules – a gain of around 150 per cent. However, this is far outweighed by the roughly 300 megajoules drawn from the electrical grid to power the lasers in the first place.

There are two main research approaches aiming to achieve viable nuclear fusion. One uses magnetic fields to contain a plasma, while the other uses lasers. NIF uses the second approach, known as inertial confinement fusion (ICF), where a tiny capsule containing hydrogen fuel is blasted with lasers, causing it to heat up and rapidly expand.

This creates an equal and opposite reaction inwards, compressing the fuel. The nuclei of hydrogen atoms then fuse together to form heavier elements and some of their mass is released as energy – just as it is in the sun.

Until now, all fusion experiments have required more energy input than they generate. NIF’s previous record, confirmed in August this year, produced an output that was equivalent to 72 per cent of the energy input from its lasers.

Today’s announcement confirms that researchers have not only reached the crucial break-even milestone, but surpassed it – albeit if you ignore the energy required to power the lasers. During the press conference, Jean-Michel Di-Nicola at LLNL said that at peak power – which NIF only achieves for a few billionths of a second – the lasers draw 500 trillion watts, which is more power than the output by the entire US national grid.

The White House Office of Science and Technology Policy’s director Arati Prabhakar said reaching the milestone was a “tremendous example of what perseverance can achieve” and that the results brings viable fusion power one step closer.

“It took not just one generation, but generations of people pursuing this goal. This duality of advancing the research, building the complex engineering systems, both sides learning from each other – this is how we do really big hard things, so this is just a beautiful example,” she said.

Jeremy Chittenden at Imperial College London says the experiment is a historic moment for fusion research. “It’s the milestone that everyone in the fusion community has been striving to achieve for 70 years now,” says Chittenden. “It’s a major vindication of the approach that we’ve been trying, for ICF, for nigh on 50 years. It’s very significant.”

Most fusion investment is currently poured into the alternative approach of magnetic confinement, in particular a reactor design called a tokamak. The Joint European Torus (JET) reactor near Oxford, UK, began operating in 1983. When running, it is the hottest point in the solar system, reaching 150 million°C (270 million°F). Earlier this year, JET sustained a reaction for 5 seconds, producing a record 59 megajoules of heat energy.

A larger and more modern replacement, the International Thermonuclear Experimental Reactor (ITER) in France, is nearing completion and its first experiments are due to start in 2025. Another reactor using the same design, the Korea Superconducting Tokamak Advanced Research (KSTAR) device, recently managed to sustain a reaction for 30 seconds at temperatures in excess of 100 million°C.

LLNL director Kim Budil said at the press conference that the delay between the experiment and the announcement was because a team of third-party experts was brought in to peer-review the data. She said that now it has been confirmed, it is likely that a laser-based power plant could be constructed within a “few decades”, but that the technology for tokamak reactors was more mature.

“There are very significant hurdles, not just in the science, but in technology,” she said. “This is one igniting capsule, one time, and to realise commercial fusion energy, you have to do many things; you have to be able to produce many, many fusion ignitions per minute, and you have to have a robust system of [laser] drivers to enable that.”

Currently, NIF can be run for an extremely short period, then it has to spend several hours cooling its components before it can be turned on once more. Approaches being tried by new commercial start-ups may prove a better way forward, says Chittenden.

“If we stick at trying to do this through massive-scale projects, which take billions of dollars to construct and tens of years to develop, it could well be that fusion arises too late to have an impact on climate change,” says Chittenden. “What I believe we really need to do is to concentrate upon increasing the diversity of approaches so that we can try to find something that has a lower impact cost and a faster turnaround, so that we might be able to get something in 10 or 15 years’ time.”

In addition to providing invaluable data for engineers working on practical reactor designs, Chittenden says NIF’s results could lead to other advances in physics, as the reactions seem even more intense and rapid than those in our sun and more like those happening in a supernova.

“We’re at extremes of pressures, densities and temperatures that we’ve never been able to access in the laboratory before,” he says. “These are processes that allow us to study what’s happening in the most extreme states of matter in the universe.”

Gianluca Sarri at Queen’s University Belfast says the findings will allow all those fusion researchers to press on, safe in the knowledge that extracting energy from fusion is possible.

“Now it’s just – and I say ‘just’ in inverted commas – a matter of refining and technical adjustments. It’s not going to happen tomorrow, obviously, because there are technical issues. We’re still far from a reactor. But we are on the right road,” he says. “In terms of clean energy, this [fusion research] is definitely the most ambitious route, but eventually will be the most rewarding because the amount of energy that you can unlock is potentially limitless.”

Sarri sayshis intuition is that the first working reactors will be tokamak devices, but that ICF research still has a vital role to play. “Both routes should go ahead, because they inform each other. There’s a lot of exchange of information between the two schemes,” he says. “The way they work is, in concept, similar.”

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