Dream of unlimited, clean fusion energy at your fingertips

The old joke is that nuclear fusion is always 30 years away. But the dream of abundant clean energy is no laughing matter when we meet an ITER researcher to catch up on progress at the reactor facility.

The sun has provided life on Earth for billions of years, creating light and heat nuclear fusion† Given that incredible power and longevity, it seems there’s hardly a better way to generate energy than by harnessing the same nuclear processes that take place in our own and other stars.

nuclear merger reactors attempt to replicate this process by fusing hydrogen atoms to create helium, releasing energy in the form of heat. By sustaining this on a large scale, a safe, clean, almost inexhaustible source of energy can be produced.

The quest started decades ago, but could a long-running joke that nuclear fusion is always 30 years from now look old?

Some hope so, after a major breakthrough during a nuclear fusion experiment at the end of 2021† This happened at the Joint European Torus (JET) research facility in Oxfordshire, UK, in a giant, donut-shaped machine called a tokamak.

Inside, superheated gases called plasmas are generated in which the fusion reactions with charged particles held in place by powerful magnetic fields. Such plasmas can reach temperatures of 150 million degrees Celsius, an unfathomable 10 times hotter than the sun’s core.

In a sustained five-second burst, researchers from the EUROfusion consortium released a record-breaking 59 megajoules (MJ) of fusion energy. This was nearly triple the previous record of 21.7 MJ achieved in 1997 at the same facility, with results being touted as “the clearest demonstration in a quarter of a century of the potential for fusion energy to deliver safe and sustainable low-carbon. supply energy.”

The results provided an important impetus in the run-up to the next phase of nuclear fusion development. A larger and more advanced version of JET, known as: ITER (meaning “the road” in Latin) is under construction on a 180-acre site in Saint-Paul-lès-Durance, southern France.

ITER, which is being built as a collaboration between 35 countries, including those in the EU, aims to further strengthen the concept of fusion. It was one of the most complicated machines ever made, and it was scheduled to begin generating its first plasma in 2025 before going high-powered around 2035 – although researchers on the project expect some delays due to the pandemic. .

Important milestone

The results at JET represent an important milestone, said Professor Tony Donné, program manager of the EUROfusion project, a large consortium of 4,800 experts, students and facilities across Europe. “It’s a huge milestone — the biggest in a long time,” he said.

“It has confirmed all the models, so it has really gained more confidence that ITER will work and do what it’s supposed to do.” While the energy generated at JET only lasted a few seconds, the intent is to ramp it up to a sustained reaction that produces energy.

The results were the culmination of years of preparation, with Prof. Donné explaining that one of the most significant developments since 1997 has been changing the inner hull of the JET vessel.

Previously, the wall was made of carbon, but this proved too reactive with the fuel mixture of deuterium and tritium, two heavier isotopes — or variants — of hydrogen used in the fusion reaction. This resulted in the formation of hydrocarbons, trapping the tritium fuel in the wall.

The rebuild, which involved 16,000 components and 4,000 tons of metal, replaced the carbon with beryllium and tungsten to reduce tritium retention. In the end, the team managed to reduce the amount of trapped fuel by a large amount, adding to the success of the recent fusion shot.

DEMO walk

In preparation for the next phase of the epic journey of fusion, upgrades to JET ensured that the configuration was in line with plans for ITER. Further in the future, the next step after ITER will be a demonstration power plant known as DEMO, designed to send electricity to the grid, leading to fusion plants becoming a commercial and industrial reality.

“ITER is a device that will create 10 times more fusion energy than the energy used to heat the plasma,” says Prof. Donné. “But because it is an experimental facility, it will not supply electricity to the grid. For that we need another device, which we call DEMO. This really gives us the basis for the first generation of fusion power plants.”

Prof Donné added: “JET has now shown that fusion is plausible. ITER must demonstrate that it is further feasible, and DEMO will have to demonstrate that it really works.”

Planned to supply up to 500 megawatts (MW) to the grid, he thinks it’s realistic for DEMO to be operational around 2050. “We hope to build DEMO much faster than we built ITER, taking (utilizing the) lessons learned,” he said.

Still, there are other important challenges that need to be overcome to get nuclear fusion going. Last but not least, while deuterium is abundant in seawater, tritium is extremely scarce and difficult to produce.

The researchers therefore plan to develop a way to generate it in the tokamak, using a “growth blanket” containing lithium. The idea is that high-energy neutrons from the fusion reactions will interact with the lithium to create tritium.

Essential energy

Prof Donné said that nuclear fusion could be a crucial green and sustainable energy source for the future. “I’d say it’s essential,” he said. “I’m not convinced that we can make the carbon dioxide transition by 2050 using only renewables, and we need other things.”

And while he says the current method of creating nuclear energy through fission is getting safer, fusion has important advantages. Proponents of ITER talk about benefits such as the lack of meltdown riskadding that nuclear fusion does not produce long-lived radioactive waste and reactor materials can be recycled or reused within 100 to 300 years.

“It is certainly much safer,” says Prof. Donné. Referring to the stigma carried by nuclear energy, he said: “What we see when we interact with the public is that very often people have never heard of nuclear fusion. But when we explain the pros and cons, I think that people become positive.”

Referring to Lev Artsimovich, aka the “father of the tokamak,” he said, “Artsimovich always said that fusion will be there when society really needs it. If we get fusion going, we really have a very safe and clean source of energy that can give us energy for thousands of years.”

---

---