Nuclear fusion gets ready for its close-up


For more than half a century, the possibility of nuclear fusion power to the modern electric grid has long been on dreams but short on reality.

On Tuesday in a town in southern France, the assembly will officially begin on a giant device designed to show nuclear fusion that has applications that could eventually lead to the construction of commercial power plants – no greenhouse gases emissions Doing and leaving produce an almost inexhaustible source of energy. No long-lived nuclear waste.

And playing a major role in this is San Diego-based General Atomics, which is building the heart of the device being assembled.

“It changes, I think, the energy economics of the entire world as a whole if fusion goes ahead,” said John Smith, director of magnetic technology at General Atomics.

The project is called ITER – Latin “For the Way” and pronounced “Eater” – and will be the world’s largest nuclear fusion device. It is an international effort with components coming from 35 partner countries including the United States.

Construction work has been underway since 2010 and overgrows the town of Caderche, covering an area of ​​approximately 445 acres. The recent arrival of a vacuum ship from South Korea paved the way for machine assembly to begin this week.

A ceremony marking the fusion experiment will be hosted by French President Emmanuel Macron and will feature commentary by officials representing the US, EU, China, Russia and other countries involved in the project.

The figurative and literal center of ITER is a central solenoid, an incredibly powerful magnet that will allow the device to create and maintain fusion on a scale never seen before by humans. The six modules, each 7 feet long, 14 feet in diameter and 250,000 pounds, will be stacked on top of each other to form solenoids.

The ITER Central Solenoid Team is standing in front of the module about to be sent to France. The modules were assembled and tested at the Center for Magnet Technology at the General Atomics campus in Poway.

(General Atomics)

A team of the company’s General Atomics scientists, engineers and workers oversees the manufacturing and testing of modules at the company’s 60,000-square-foot warehouse in Pawe. A seventh module, a spare, is also being built when something is wrong with another.

Each module is surrounded by 3.6 miles of conductor segments and wrapped with six layers of insulating tape totaling more than 180 miles.

Once upon a time, each module would be transported to the Texas Gulf Coast by a specially designed trailer, then shipped to Marseille, France before being taken to ITER. The first module is expected to head to France in the fall.

“I’ve been to the ITER site, and you’re standing down where the whole device goes in and you look up and you go, ‘Wow, this is big,” Smith said.

ITER has been dubbed the “world’s largest science project”, but its goals are rarely insignificant. By trying to demonstrate that Fusion could someday lead power generation on a commercial scale, the project requires a replication of less than what the Sun makes.

Nuclear fusion differs from nuclear fission, a process used in commercial nuclear power plants, such as the now-closed San Onofre Nuclear Generating Station. Fission splits the nucleus of atoms to create strength, while fusion hydrogen collides the nucleus and collides into helium atoms that release a tremendous amount of energy.

If there is a disturbance during the fusion process, the plasma cools down within seconds, and the reaction stops, preventing the risk of a meltdown or accident similar to that in Fukushima.

While operators of fission plants have to deal with radioactive spent fuel, or waste, that is left behind, the active components in the fusion reactor are sufficient for recycled or reused materials within 100 years .

Fusion technology was important in the development of hydrogen bombs, but as an energy source, fusion reactors do not exist. In fact, fusion power has only been generated for a very short time in the laboratory.

ITER “will try to run a fusion experiment for several hundred seconds, which has never been done at the power level,” Smith said. “And then most importantly, they’re going to show what they call ‘Fusion Gain’. That’s where the power it takes to create a Fusion Reaction will actually get 10 times more power than the Reaction they take .

In the fusion process, a massive, donut-shaped chamber called tokamak heats hydrogen until it becomes a cloud-like ionized plasma, which is then shaped and controlled by 10,000 tons of superconducting magnets. . Fusion occurs when plasma reaches 150 million degrees Celsius – 10 times warmer than the Sun’s core.

High-energy neutrons from fusion transmit energy as heat, and the water circulating in the walls of the tokamak absorbs the remaining heat and creates steam, which – in a commercial power plant – power through a steam turbine Will generate

Components for ITER Tokamak are coming from project partners all over the world.

“The creation of a piece of machine would be like assembling a three-dimensional puzzle on a complex timeline,” Bernard Bigot, director of the ITER, said in a statement. “We have a complex script over the next few years.”

The initial demonstration of ITER’s own functionality – called “first plasma” by scientists and engineers – is scheduled for December 2025.

“Maybe 15 years ago, I could have my doubts about coordinating such a complex effort”, Smith said. “Now that I’ve seen it being brought together and then working closely with groups around the world, I have no doubt that it will come together.”

Fusion has its share of doubts, however. The development of commercial fusion reactors has been discussed since the 1950s, hinting an ongoing joke in the energy industry that fusion as a power source is always 30 years away.

ITER is running behind schedule and over budget. Twenty years ago, the project cost about $ 7 billion, but more recent estimates say that by the time this project gets underway, the cost could be up to 10 times higher.

The US contributes about 9% of ITER’s costs.

Smith said he is confident that ITER can achieve its goals, but commercial nuclear fusion plants will still take years to become a reality.

“There should be another demonstration reactor after ITER,” Smith said. “You cannot go to the power plant from ITER. There is something in between. ”

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