Nuclear fusion gets ready for its close-up

San Diego Union-Tribune

July 28, 2020 11:56 AM PT

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

But Tuesday in a town in southern France, assembly will officially begin on a massive device designed to show nuclear fusion has applications that can eventually lead to the construction of commercial power plants — generating a virtually inexhaustible source of energy while emitting no greenhouse gases and leaving no long-lived nuclear waste behind.

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

“It changes, I think, the whole world’s energy economics entirely if fusion goes forward,” 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’s an international effort with components coming from 35 partner countries, including the United States.

Construction has been underway since 2010 and rises high over the town of Cadarache on a site covering about 445 acres. The recent arrival of a vacuum vessel 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 remarks by officials representing the U.S., the European Union, 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 sustain fusion on a scale never seen before by humans. Six modules, each 7 feet tall, 14 feet in diameter and 250,000 pounds, will be stacked atop one another to create the solenoid.

A team of General Atomics scientists, engineers and workers at the company’s 60,000-square-foot warehouse in Poway have overseen the fabricating and testing of the modules. A seventh module, a spare, is also being constructed in case something goes wrong with one of the others.

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

One at a time, each module will be transported by a specially designed trailer to the Texas Gulf Coast, then shipped to Marseilles, France, before getting trucked to ITER. The first module is expected to head to France in the fall.

“I’ve been to the ITER site, and you stand at the bottom of 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 hardly trivial. By trying to demonstrate that fusion can some day lead to power generation on a commercial scale, the project requires replicating nothing less than what the sun creates.

Nuclear fusion differs from nuclear fission, which is the process used in commercial nuclear power plants, such as the now-shuttered San Onofre Nuclear Generating Station. Fission splits the nuclei of atoms to create power, while fusion causes hydrogen nuclei to collide and fuse into helium atoms that release tremendous amounts of energy.

If any disturbance occurs during the fusion process, the plasma cools within seconds, and the reaction stops, thereby preventing the risk of a meltdown or accident like the one at Fukushima.

While operators of fission plants have to cope with radioactive spent fuel, or waste, that is left behind, components activated in a fusion reactor are low enough for the materials to be recycled or reused within 100 years.

Fusion technology was critical in the development of the hydrogen bomb, but as an energy source, no fusion reactors exist. In fact, fusion power has been generated only for very short periods in the laboratory.

ITER will try “to run a fusion experiment for several hundred seconds, which has never been done at the power levels talked about,” Smith said. “And then most importantly, they’re going to show what they call the ‘fusion gain.’ That’s where the power that it takes to create the fusion reaction, they’ll actually get 10 times more power out of the reaction than what they put in.”

In the fusion process, a huge, doughnut-shaped chamber called a 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 the plasma reaches 150 million degrees Celsius — 10 times hotter than the sun’s core.

The high-energy neutrons from fusion transmit energy as heat, and water circulating in the walls of the Tokamak absorbs the escaped heat and makes steam, which — in a commercial power plant — would generate electricity via steam turbines.

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

“Constructing the machine piece by piece will be like assembling a three-dimensional puzzle on an intricate timeline,” Bernhard Bigot, ITER’s director-general, said in a statement. “We have a complicated script to follow over the next few years.”

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

“Maybe 15 years ago, I might have had my doubts” about coordinating such a complex effort, Smith said. “Now that I’ve seen it being brought together and then working intimately with the worldwide group, I have no doubt that it will come together.”

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

ITER has been running behind schedule and over budget. Twenty years ago, the project was expected to cost about $7 billion, but more recent estimates say that by the time the project is operational, the cost could be 10 times higher.

The U.S. contribution accounts for about 9% of ITER’s costs.

Smith said he’s confident ITER can achieve its goals, but it will still take years before commercial nuclear fusion plants become a reality.

“There has to be another demonstration reactor after ITER,” Smith said. “You can’t go from ITER to a power plant. There’s something in between.”